5
This document describes the Bazaar internals and the development process.
6
It's meant for people interested in developing Bazaar, and some parts will
7
also be useful to people developing Bazaar plugins.
9
If you have any questions or something seems to be incorrect, unclear or
10
missing, please talk to us in ``irc://irc.freenode.net/#bzr``, or write to
11
the Bazaar mailing list. To propose a correction or addition to this
12
document, send a merge request or new text to the mailing list.
14
The current version of this document is available in the file
15
``doc/developers/HACKING.txt`` in the source tree, or at
16
http://doc.bazaar-vcs.org/bzr.dev/en/developer-guide/HACKING.html
19
`Bazaar Developer Documentation Catalog <../../developers/index.html>`_.
27
Exploring the Bazaar Platform
28
=============================
30
Before making changes, it's a good idea to explore the work already
31
done by others. Perhaps the new feature or improvement you're looking
32
for is available in another plug-in already? If you find a bug,
33
perhaps someone else has already fixed it?
35
To answer these questions and more, take a moment to explore the
36
overall Bazaar Platform. Here are some links to browse:
38
* The Plugins page on the Wiki - http://bazaar-vcs.org/BzrPlugins
40
* The Bazaar product family on Launchpad - https://launchpad.net/bazaar
42
* Bug Tracker for the core product - https://bugs.launchpad.net/bzr/
44
* Blueprint Tracker for the core product - https://blueprints.launchpad.net/bzr/
46
If nothing else, perhaps you'll find inspiration in how other developers
47
have solved their challenges.
50
Planning and Discussing Changes
51
===============================
53
There is a very active community around Bazaar. Mostly we meet on IRC
54
(#bzr on irc.freenode.net) and on the mailing list. To join the Bazaar
55
community, see http://bazaar-vcs.org/BzrSupport.
57
If you are planning to make a change, it's a very good idea to mention it
58
on the IRC channel and/or on the mailing list. There are many advantages
59
to involving the community before you spend much time on a change.
62
* you get to build on the wisdom on others, saving time
64
* if others can direct you to similar code, it minimises the work to be done
66
* it assists everyone in coordinating direction, priorities and effort.
68
In summary, maximising the input from others typically minimises the
69
total effort required to get your changes merged. The community is
70
friendly, helpful and always keen to welcome newcomers.
73
Bazaar Development in a Nutshell
74
================================
76
Looking for a 10 minute introduction to submitting a change?
77
See http://bazaar-vcs.org/BzrGivingBack.
79
TODO: Merge that Wiki page into this document.
82
Understanding the Development Process
83
=====================================
85
The development team follows many best-practices including:
87
* a public roadmap and planning process in which anyone can participate
89
* time based milestones everyone can work towards and plan around
91
* extensive code review and feedback to contributors
93
* complete and rigorous test coverage on any code contributed
95
* automated validation that all tests still pass before code is merged
96
into the main code branch.
98
The key tools we use to enable these practices are:
100
* Launchpad - https://launchpad.net/
102
* Bazaar - http://bazaar-vcs.org/
104
* Bundle Buggy - http://bundlebuggy.aaronbentley.com/
106
* Patch Queue Manager - https://launchpad.net/pqm/
108
For further information, see http://bazaar-vcs.org/BzrDevelopment.
111
A Closer Look at the Merge & Review Process
112
===========================================
114
If you'd like to propose a change, please post to the
115
bazaar@lists.canonical.com list with a bundle, patch, or link to a
116
branch. Put '[PATCH]' or '[MERGE]' in the subject so Bundle Buggy
117
can pick it out, and explain the change in the email message text.
118
Remember to update the NEWS file as part of your change if it makes any
119
changes visible to users or plugin developers. Please include a diff
120
against mainline if you're giving a link to a branch.
122
You can generate a bundle like this::
124
bzr bundle > mybundle.patch
126
A .patch extension is recommended instead of .bundle as many mail clients
127
will send the latter as a binary file. If a bundle would be too long or your
128
mailer mangles whitespace (e.g. implicitly converts Unix newlines to DOS
129
newlines), use the merge-directive command instead like this::
131
bzr merge-directive http://bazaar-vcs.org http://example.org/my_branch > my_directive.patch
133
See the help for details on the arguments to merge-directive.
135
Please do **NOT** put [PATCH] or [MERGE] in the subject line if you don't
136
want it to be merged. If you want comments from developers rather than
137
to be merged, you can put '[RFC]' in the subject line.
139
Anyone is welcome to review code. There are broadly three gates for
142
* Doesn't reduce test coverage: if it adds new methods or commands,
143
there should be tests for them. There is a good test framework
144
and plenty of examples to crib from, but if you are having trouble
145
working out how to test something feel free to post a draft patch
148
* Doesn't reduce design clarity, such as by entangling objects
149
we're trying to separate. This is mostly something the more
150
experienced reviewers need to help check.
152
* Improves bugs, features, speed, or code simplicity.
154
Code that goes in should pass all three. The core developers take care
155
to keep the code quality high and understandable while recognising that
156
perfect is sometimes the enemy of good. (It is easy for reviews to make
157
people notice other things which should be fixed but those things should
158
not hold up the original fix being accepted. New things can easily be
159
recorded in the Bug Tracker instead.)
161
Anyone can "vote" on the mailing list. Core developers can also vote using
162
Bundle Buggy. Here are the voting codes and their explanations.
164
:approve: Reviewer wants this submission merged.
165
:tweak: Reviewer wants this submission merged with small changes. (No
167
:abstain: Reviewer does not intend to vote on this patch.
168
:resubmit: Please make changes and resubmit for review.
169
:reject: Reviewer doesn't want this kind of change merged.
170
:comment: Not really a vote. Reviewer just wants to comment, for now.
172
If a change gets two approvals from core reviewers, and no rejections,
173
then it's OK to come in. Any of the core developers can bring it into the
174
bzr.dev trunk and backport it to maintenance branches if required. The
175
Release Manager will merge the change into the branch for a pending
176
release, if any. As a guideline, core developers usually merge their own
177
changes and volunteer to merge other contributions if they were the second
178
reviewer to agree to a change.
180
To track the progress of proposed changes, use Bundle Buggy. See
181
http://bundlebuggy.aaronbentley.com/help for a link to all the
182
outstanding merge requests together with an explanation of the columns.
183
Bundle Buggy will also mail you a link to track just your change.
186
Preparing a Sandbox for Making Changes to Bazaar
187
================================================
189
Bazaar supports many ways of organising your work. See
190
http://bazaar-vcs.org/SharedRepositoryLayouts for a summary of the
191
popular alternatives.
193
Of course, the best choice for you will depend on numerous factors:
194
the number of changes you may be making, the complexity of the changes, etc.
195
As a starting suggestion though:
197
* create a local copy of the main development branch (bzr.dev) by using
200
bzr branch http://bazaar-vcs.org/bzr/bzr.dev/ bzr.dev
202
* keep your copy of bzr.dev prestine (by not developing in it) and keep
203
it up to date (by using bzr pull)
205
* create a new branch off your local bzr.dev copy for each issue
206
(bug or feature) you are working on.
208
This approach makes it easy to go back and make any required changes
209
after a code review. Resubmitting the change is then simple with no
210
risk of accidentially including edits related to other issues you may
211
be working on. After the changes for an issue are accepted and merged,
212
the associated branch can be deleted or archived as you wish.
215
Navigating the Code Base
216
========================
218
.. Was at <http://bazaar-vcs.org/NewDeveloperIntroduction>
220
Some of the key files in this directory are:
223
The command you run to start Bazaar itself. This script is pretty
224
short and just does some checks then jumps into bzrlib.
227
This file covers a brief introduction to Bazaar and lists some of its
231
Summary of changes in each Bazaar release that can affect users or
235
Installs Bazaar system-wide or to your home directory. To perform
236
development work on Bazaar it is not required to run this file - you
237
can simply run the bzr command from the top level directory of your
238
development copy. Note: That if you run setup.py this will create a
239
'build' directory in your development branch. There's nothing wrong
240
with this but don't be confused by it. The build process puts a copy
241
of the main code base into this build directory, along with some other
242
files. You don't need to go in here for anything discussed in this
246
Possibly the most exciting folder of all, bzrlib holds the main code
247
base. This is where you will go to edit python files and contribute to
251
Holds documentation on a whole range of things on Bazaar from the
252
origination of ideas within the project to information on Bazaar
253
features and use cases. Within this directory there is a subdirectory
254
for each translation into a human language. All the documentation
255
is in the ReStructuredText markup language.
258
Documentation specifically targetted at Bazaar and plugin developers.
259
(Including this document.)
263
Automatically-generated API reference information is available at
264
<http://starship.python.net/crew/mwh/bzrlibapi/>.
265
(There is an experimental editable version at
266
<http://starship.python.net/crew/mwh/bzrlibapi-oe/>.)
267
See also the `Essential Domain Classes`_
268
section of this guide.
274
The Importance of Testing
275
=========================
277
Reliability is a critical success factor for any Version Control System.
278
We want Bazaar to be highly reliable across multiple platforms while
279
evolving over time to meet the needs of its community.
281
In a nutshell, this is want we expect and encourage:
283
* New functionality should have test cases. Preferably write the
284
test before writing the code.
286
In general, you can test at either the command-line level or the
287
internal API level. See Writing tests below for more detail.
289
* Try to practice Test-Driven Development: before fixing a bug, write a
290
test case so that it does not regress. Similarly for adding a new
291
feature: write a test case for a small version of the new feature before
292
starting on the code itself. Check the test fails on the old code, then
293
add the feature or fix and check it passes.
295
By doing these things, the Bazaar team gets increased confidence that
296
changes do what they claim to do, whether provided by the core team or
297
by community members. Equally importantly, we can be surer that changes
298
down the track do not break new features or bug fixes that you are
301
As of May 2008, Bazaar ships with a test suite containing over 12000 tests
302
and growing. We are proud of it and want to remain so. As community
303
members, we all benefit from it. Would you trust version control on
304
your project to a product *without* a test suite like Bazaar has?
307
Running the Test Suite
308
======================
310
Currently, bzr selftest is used to invoke tests.
311
You can provide a pattern argument to run a subset. For example,
312
to run just the blackbox tests, run::
314
./bzr selftest -v blackbox
316
To skip a particular test (or set of tests), use the --exclude option
317
(shorthand -x) like so::
319
./bzr selftest -v -x blackbox
321
To ensure that all tests are being run and succeeding, you can use the
322
--strict option which will fail if there are any missing features or known
325
./bzr selftest --strict
327
To list tests without running them, use the --list-only option like so::
329
./bzr selftest --list-only
331
This option can be combined with other selftest options (like -x) and
332
filter patterns to understand their effect.
334
Once you understand how to create a list of tests, you can use the --load-list
335
option to run only a restricted set of tests that you kept in a file, one test
336
id by line. Keep in mind that this will never be sufficient to validate your
337
modifications, you still need to run the full test suite for that, but using it
338
can help in some cases (like running only the failed tests for some time)::
340
./bzr selftest -- load-list my_failing_tests
342
This option can also be combined with other selftest options, including
343
patterns. It has some drawbacks though, the list can become out of date pretty
344
quick when doing Test Driven Development.
346
To address this concern, there is another way to run a restricted set of tests:
347
the --starting-with option will run only the tests whose name starts with the
348
specified string. It will also avoid loading the other tests and as a
349
consequence starts running your tests quicker::
351
./bzr selftest --starting-with bzrlib.blackbox
353
This option can be combined with all the other selftest options including
354
--load-list. The later is rarely used but allows to run a subset of a list of
355
failing tests for example.
357
Test suite debug flags
358
----------------------
360
Similar to the global ``-Dfoo`` debug options, bzr selftest accepts
361
``-E=foo`` debug flags. These flags are:
363
:allow_debug: do *not* clear the global debug flags when running a test.
364
This can provide useful logging to help debug test failures when used
365
with e.g. ``bzr -Dhpss selftest -E=allow_debug``
371
In general tests should be placed in a file named test_FOO.py where
372
FOO is the logical thing under test. That file should be placed in the
373
tests subdirectory under the package being tested.
375
For example, tests for merge3 in bzrlib belong in bzrlib/tests/test_merge3.py.
376
See bzrlib/tests/test_sampler.py for a template test script.
378
Tests can be written for the UI or for individual areas of the library.
379
Choose whichever is appropriate: if adding a new command, or a new command
380
option, then you should be writing a UI test. If you are both adding UI
381
functionality and library functionality, you will want to write tests for
382
both the UI and the core behaviours. We call UI tests 'blackbox' tests
383
and they are found in ``bzrlib/tests/blackbox/*.py``.
385
When writing blackbox tests please honour the following conventions:
387
1. Place the tests for the command 'name' in
388
bzrlib/tests/blackbox/test_name.py. This makes it easy for developers
389
to locate the test script for a faulty command.
391
2. Use the 'self.run_bzr("name")' utility function to invoke the command
392
rather than running bzr in a subprocess or invoking the
393
cmd_object.run() method directly. This is a lot faster than
394
subprocesses and generates the same logging output as running it in a
395
subprocess (which invoking the method directly does not).
397
3. Only test the one command in a single test script. Use the bzrlib
398
library when setting up tests and when evaluating the side-effects of
399
the command. We do this so that the library api has continual pressure
400
on it to be as functional as the command line in a simple manner, and
401
to isolate knock-on effects throughout the blackbox test suite when a
402
command changes its name or signature. Ideally only the tests for a
403
given command are affected when a given command is changed.
405
4. If you have a test which does actually require running bzr in a
406
subprocess you can use ``run_bzr_subprocess``. By default the spawned
407
process will not load plugins unless ``--allow-plugins`` is supplied.
413
We make selective use of doctests__. In general they should provide
414
*examples* within the API documentation which can incidentally be tested. We
415
don't try to test every important case using doctests -- regular Python
416
tests are generally a better solution.
418
Most of these are in ``bzrlib/doc/api``. More additions are welcome.
420
__ http://docs.python.org/lib/module-doctest.html
423
Skipping tests and test requirements
424
------------------------------------
426
In our enhancements to unittest we allow for some addition results beyond
427
just success or failure.
429
If a test can't be run, it can say that it's skipped. This is typically
430
used in parameterized tests - for example if a transport doesn't support
431
setting permissions, we'll skip the tests that relating to that. ::
434
return self.branch_format.initialize(repo.bzrdir)
435
except errors.UninitializableFormat:
436
raise tests.TestSkipped('Uninitializable branch format')
438
Raising TestSkipped is a good idea when you want to make it clear that the
439
test was not run, rather than just returning which makes it look as if it
442
Several different cases are distinguished:
445
Generic skip; the only type that was present up to bzr 0.18.
448
The test doesn't apply to the parameters with which it was run.
449
This is typically used when the test is being applied to all
450
implementations of an interface, but some aspects of the interface
451
are optional and not present in particular concrete
452
implementations. (Some tests that should raise this currently
453
either silently return or raise TestSkipped.) Another option is
454
to use more precise parameterization to avoid generating the test
458
**(Not implemented yet)**
459
The test can't be run because of an inherent limitation of the
460
environment, such as not having symlinks or not supporting
464
The test can't be run because a dependency (typically a Python
465
library) is not available in the test environment. These
466
are in general things that the person running the test could fix
467
by installing the library. It's OK if some of these occur when
468
an end user runs the tests or if we're specifically testing in a
469
limited environment, but a full test should never see them.
472
The test exists but is known to fail, for example because the
473
code to fix it hasn't been run yet. Raising this allows
474
you to distinguish these failures from the ones that are not
475
expected to fail. This could be conditionally raised if something
476
is broken on some platforms but not on others.
478
We plan to support three modes for running the test suite to control the
479
interpretation of these results. Strict mode is for use in situations
480
like merges to the mainline and releases where we want to make sure that
481
everything that can be tested has been tested. Lax mode is for use by
482
developers who want to temporarily tolerate some known failures. The
483
default behaviour is obtained by ``bzr selftest`` with no options, and
484
also (if possible) by running under another unittest harness.
486
======================= ======= ======= ========
487
result strict default lax
488
======================= ======= ======= ========
489
TestSkipped pass pass pass
490
TestNotApplicable pass pass pass
491
TestPlatformLimit pass pass pass
492
TestDependencyMissing fail pass pass
493
KnownFailure fail pass pass
494
======================= ======= ======= ========
497
Test feature dependencies
498
-------------------------
500
Rather than manually checking the environment in each test, a test class
501
can declare its dependence on some test features. The feature objects are
502
checked only once for each run of the whole test suite.
504
For historical reasons, as of May 2007 many cases that should depend on
505
features currently raise TestSkipped.)
509
class TestStrace(TestCaseWithTransport):
511
_test_needs_features = [StraceFeature]
513
This means all tests in this class need the feature. The feature itself
514
should provide a ``_probe`` method which is called once to determine if
517
These should generally be equivalent to either TestDependencyMissing or
518
sometimes TestPlatformLimit.
524
Known failures are when a test exists but we know it currently doesn't
525
work, allowing the test suite to still pass. These should be used with
526
care, we don't want a proliferation of quietly broken tests. It might be
527
appropriate to use them if you've committed a test for a bug but not the
528
fix for it, or if something works on Unix but not on Windows.
531
Testing exceptions and errors
532
-----------------------------
534
It's important to test handling of errors and exceptions. Because this
535
code is often not hit in ad-hoc testing it can often have hidden bugs --
536
it's particularly common to get NameError because the exception code
537
references a variable that has since been renamed.
539
.. TODO: Something about how to provoke errors in the right way?
541
In general we want to test errors at two levels:
543
1. A test in ``test_errors.py`` checking that when the exception object is
544
constructed with known parameters it produces an expected string form.
545
This guards against mistakes in writing the format string, or in the
546
``str`` representations of its parameters. There should be one for
547
each exception class.
549
2. Tests that when an api is called in a particular situation, it raises
550
an error of the expected class. You should typically use
551
``assertRaises``, which in the Bazaar test suite returns the exception
552
object to allow you to examine its parameters.
554
In some cases blackbox tests will also want to check error reporting. But
555
it can be difficult to provoke every error through the commandline
556
interface, so those tests are only done as needed -- eg in response to a
557
particular bug or if the error is reported in an unusual way(?) Blackbox
558
tests should mostly be testing how the command-line interface works, so
559
should only test errors if there is something particular to the cli in how
560
they're displayed or handled.
566
The Python ``warnings`` module is used to indicate a non-fatal code
567
problem. Code that's expected to raise a warning can be tested through
570
The test suite can be run with ``-Werror`` to check no unexpected errors
573
However, warnings should be used with discretion. It's not an appropriate
574
way to give messages to the user, because the warning is normally shown
575
only once per source line that causes the problem. You should also think
576
about whether the warning is serious enought that it should be visible to
577
users who may not be able to fix it.
580
Interface implementation testing and test scenarios
581
---------------------------------------------------
583
There are several cases in Bazaar of multiple implementations of a common
584
conceptual interface. ("Conceptual" because
585
it's not necessary for all the implementations to share a base class,
586
though they often do.) Examples include transports and the working tree,
587
branch and repository classes.
589
In these cases we want to make sure that every implementation correctly
590
fulfils the interface requirements. For example, every Transport should
591
support the ``has()`` and ``get()`` and ``clone()`` methods. We have a
592
sub-suite of tests in ``test_transport_implementations``. (Most
593
per-implementation tests are in submodules of ``bzrlib.tests``, but not
594
the transport tests at the moment.)
596
These tests are repeated for each registered Transport, by generating a
597
new TestCase instance for the cross product of test methods and transport
598
implementations. As each test runs, it has ``transport_class`` and
599
``transport_server`` set to the class it should test. Most tests don't
600
access these directly, but rather use ``self.get_transport`` which returns
601
a transport of the appropriate type.
603
The goal is to run per-implementation only tests that relate to that
604
particular interface. Sometimes we discover a bug elsewhere that happens
605
with only one particular transport. Once it's isolated, we can consider
606
whether a test should be added for that particular implementation,
607
or for all implementations of the interface.
609
The multiplication of tests for different implementations is normally
610
accomplished by overriding the ``test_suite`` function used to load
611
tests from a module. This function typically loads all the tests,
612
then applies a TestProviderAdapter to them, which generates a longer
613
suite containing all the test variations.
619
Some utilities are provided for generating variations of tests. This can
620
be used for per-implementation tests, or other cases where the same test
621
code needs to run several times on different scenarios.
623
The general approach is to define a class that provides test methods,
624
which depend on attributes of the test object being pre-set with the
625
values to which the test should be applied. The test suite should then
626
also provide a list of scenarios in which to run the tests.
628
Typically ``multiply_tests_from_modules`` should be called from the test
629
module's ``test_suite`` function.
632
Essential Domain Classes
633
########################
635
Introducing the Object Model
636
============================
638
The core domain objects within the bazaar model are:
648
Transports are explained below. See http://bazaar-vcs.org/Classes/
649
for an introduction to the other key classes.
654
The ``Transport`` layer handles access to local or remote directories.
655
Each Transport object acts like a logical connection to a particular
656
directory, and it allows various operations on files within it. You can
657
*clone* a transport to get a new Transport connected to a subdirectory or
660
Transports are not used for access to the working tree. At present
661
working trees are always local and they are accessed through the regular
662
Python file io mechanisms.
667
Transports work in URLs. Take note that URLs are by definition only
668
ASCII - the decision of how to encode a Unicode string into a URL must be
669
taken at a higher level, typically in the Store. (Note that Stores also
670
escape filenames which cannot be safely stored on all filesystems, but
671
this is a different level.)
673
The main reason for this is that it's not possible to safely roundtrip a
674
URL into Unicode and then back into the same URL. The URL standard
675
gives a way to represent non-ASCII bytes in ASCII (as %-escapes), but
676
doesn't say how those bytes represent non-ASCII characters. (They're not
677
guaranteed to be UTF-8 -- that is common but doesn't happen everywhere.)
679
For example if the user enters the url ``http://example/%e0`` there's no
680
way to tell whether that character represents "latin small letter a with
681
grave" in iso-8859-1, or "latin small letter r with acute" in iso-8859-2
682
or malformed UTF-8. So we can't convert their URL to Unicode reliably.
684
Equally problematic if we're given a url-like string containing non-ascii
685
characters (such as the accented a) we can't be sure how to convert that
686
to the correct URL, because we don't know what encoding the server expects
687
for those characters. (Although this is not totally reliable we might still
688
accept these and assume they should be put into UTF-8.)
690
A similar edge case is that the url ``http://foo/sweet%2Fsour`` contains
691
one directory component whose name is "sweet/sour". The escaped slash is
692
not a directory separator. If we try to convert URLs to regular Unicode
693
paths this information will be lost.
695
This implies that Transports must natively deal with URLs; for simplicity
696
they *only* deal with URLs and conversion of other strings to URLs is done
697
elsewhere. Information they return, such as from ``list_dir``, is also in
698
the form of URL components.
701
Coding Style Guidelines
702
#######################
707
``hasattr`` should not be used because it swallows exceptions including
708
``KeyboardInterrupt``. Instead, say something like ::
710
if getattr(thing, 'name', None) is None
716
Please write PEP-8__ compliant code.
718
__ http://www.python.org/peps/pep-0008.html
720
One often-missed requirement is that the first line of docstrings
721
should be a self-contained one-sentence summary.
723
We use 4 space indents for blocks, and never use tab characters. (In vim,
726
Lines should be no more than 79 characters if at all possible.
727
Lines that continue a long statement may be indented in either of
730
within the parenthesis or other character that opens the block, e.g.::
736
or indented by four spaces::
742
The first is considered clearer by some people; however it can be a bit
743
harder to maintain (e.g. when the method name changes), and it does not
744
work well if the relevant parenthesis is already far to the right. Avoid
747
self.legbone.kneebone.shinbone.toebone.shake_it(one,
753
self.legbone.kneebone.shinbone.toebone.shake_it(one,
759
self.legbone.kneebone.shinbone.toebone.shake_it(
762
For long lists, we like to add a trailing comma and put the closing
763
character on the following line. This makes it easier to add new items in
766
from bzrlib.goo import (
772
There should be spaces between function paramaters, but not between the
773
keyword name and the value::
775
call(1, 3, cheese=quark)
779
;(defface my-invalid-face
780
; '((t (:background "Red" :underline t)))
781
; "Face used to highlight invalid constructs or other uglyties"
784
(defun my-python-mode-hook ()
785
;; setup preferred indentation style.
786
(setq fill-column 79)
787
(setq indent-tabs-mode nil) ; no tabs, never, I will not repeat
788
; (font-lock-add-keywords 'python-mode
789
; '(("^\\s *\t" . 'my-invalid-face) ; Leading tabs
790
; ("[ \t]+$" . 'my-invalid-face) ; Trailing spaces
791
; ("^[ \t]+$" . 'my-invalid-face)); Spaces only
795
(add-hook 'python-mode-hook 'my-python-mode-hook)
797
The lines beginning with ';' are comments. They can be activated
798
if one want to have a strong notice of some tab/space usage
805
* Imports should be done at the top-level of the file, unless there is
806
a strong reason to have them lazily loaded when a particular
807
function runs. Import statements have a cost, so try to make sure
808
they don't run inside hot functions.
810
* Module names should always be given fully-qualified,
811
i.e. ``bzrlib.hashcache`` not just ``hashcache``.
817
Functions, methods or members that are "private" to bzrlib are given
818
a leading underscore prefix. Names without a leading underscore are
819
public not just across modules but to programmers using bzrlib as an
820
API. As a consequence, a leading underscore is appropriate for names
821
exposed across modules but that are not to be exposed to bzrlib API
824
We prefer class names to be concatenated capital words (``TestCase``)
825
and variables, methods and functions to be lowercase words joined by
826
underscores (``revision_id``, ``get_revision``).
828
For the purposes of naming some names are treated as single compound
829
words: "filename", "revno".
831
Consider naming classes as nouns and functions/methods as verbs.
833
Try to avoid using abbreviations in names, because there can be
834
inconsistency if other people use the full name.
840
``revision_id`` not ``rev_id`` or ``revid``
842
Functions that transform one thing to another should be named ``x_to_y``
843
(not ``x2y`` as occurs in some old code.)
849
Python destructors (``__del__``) work differently to those of other
850
languages. In particular, bear in mind that destructors may be called
851
immediately when the object apparently becomes unreferenced, or at some
852
later time, or possibly never at all. Therefore we have restrictions on
853
what can be done inside them.
855
0. If you think you need to use a ``__del__`` method ask another
856
developer for alternatives. If you do need to use one, explain
859
1. Never rely on a ``__del__`` method running. If there is code that
860
must run, do it from a ``finally`` block instead.
862
2. Never ``import`` from inside a ``__del__`` method, or you may crash the
865
3. In some places we raise a warning from the destructor if the object
866
has not been cleaned up or closed. This is considered OK: the warning
867
may not catch every case but it's still useful sometimes.
873
In some places we have variables which point to callables that construct
874
new instances. That is to say, they can be used a lot like class objects,
875
but they shouldn't be *named* like classes:
877
> I think that things named FooBar should create instances of FooBar when
878
> called. Its plain confusing for them to do otherwise. When we have
879
> something that is going to be used as a class - that is, checked for via
880
> isinstance or other such idioms, them I would call it foo_class, so that
881
> it is clear that a callable is not sufficient. If it is only used as a
882
> factory, then yes, foo_factory is what I would use.
888
Several places in Bazaar use (or will use) a registry, which is a
889
mapping from names to objects or classes. The registry allows for
890
loading in registered code only when it's needed, and keeping
891
associated information such as a help string or description.
897
To make startup time faster, we use the ``bzrlib.lazy_import`` module to
898
delay importing modules until they are actually used. ``lazy_import`` uses
899
the same syntax as regular python imports. So to import a few modules in a
902
from bzrlib.lazy_import import lazy_import
903
lazy_import(globals(), """
912
revision as _mod_revision,
914
import bzrlib.transport
918
At this point, all of these exist as a ``ImportReplacer`` object, ready to
919
be imported once a member is accessed. Also, when importing a module into
920
the local namespace, which is likely to clash with variable names, it is
921
recommended to prefix it as ``_mod_<module>``. This makes it clearer that
922
the variable is a module, and these object should be hidden anyway, since
923
they shouldn't be imported into other namespaces.
925
While it is possible for ``lazy_import()`` to import members of a module
926
when using the ``from module import member`` syntax, it is recommended to
927
only use that syntax to load sub modules ``from module import submodule``.
928
This is because variables and classes can frequently be used without
929
needing a sub-member for example::
931
lazy_import(globals(), """
932
from module import MyClass
936
return isinstance(x, MyClass)
938
This will incorrectly fail, because ``MyClass`` is a ``ImportReplacer``
939
object, rather than the real class.
941
It also is incorrect to assign ``ImportReplacer`` objects to other variables.
942
Because the replacer only knows about the original name, it is unable to
943
replace other variables. The ``ImportReplacer`` class will raise an
944
``IllegalUseOfScopeReplacer`` exception if it can figure out that this
945
happened. But it requires accessing a member more than once from the new
946
variable, so some bugs are not detected right away.
952
The null revision is the ancestor of all revisions. Its revno is 0, its
953
revision-id is ``null:``, and its tree is the empty tree. When referring
954
to the null revision, please use ``bzrlib.revision.NULL_REVISION``. Old
955
code sometimes uses ``None`` for the null revision, but this practice is
959
Object string representations
960
=============================
962
Python prints objects using their ``__repr__`` method when they are
963
written to logs, exception tracebacks, or the debugger. We want
964
objects to have useful representations to help in determining what went
967
If you add a new class you should generally add a ``__repr__`` method
968
unless there is an adequate method in a parent class. There should be a
971
Representations should typically look like Python constructor syntax, but
972
they don't need to include every value in the object and they don't need
973
to be able to actually execute. They're to be read by humans, not
974
machines. Don't hardcode the classname in the format, so that we get the
975
correct value if the method is inherited by a subclass. If you're
976
printing attributes of the object, including strings, you should normally
977
use ``%r`` syntax (to call their repr in turn).
979
Try to avoid the representation becoming more than one or two lines long.
980
(But balance this against including useful information, and simplicity of
983
Because repr methods are often called when something has already gone
984
wrong, they should be written somewhat more defensively than most code.
985
The object may be half-initialized or in some other way in an illegal
986
state. The repr method shouldn't raise an exception, or it may hide the
987
(probably more useful) underlying exception.
992
return '%s(%r)' % (self.__class__.__name__,
999
A bare ``except`` statement will catch all exceptions, including ones that
1000
really should terminate the program such as ``MemoryError`` and
1001
``KeyboardInterrupt``. They should rarely be used unless the exception is
1002
later re-raised. Even then, think about whether catching just
1003
``Exception`` (which excludes system errors in Python2.5 and later) would
1014
We have a commitment to 6 months API stability - any supported symbol in a
1015
release of bzr MUST NOT be altered in any way that would result in
1016
breaking existing code that uses it. That means that method names,
1017
parameter ordering, parameter names, variable and attribute names etc must
1018
not be changed without leaving a 'deprecated forwarder' behind. This even
1019
applies to modules and classes.
1021
If you wish to change the behaviour of a supported API in an incompatible
1022
way, you need to change its name as well. For instance, if I add an optional keyword
1023
parameter to branch.commit - that's fine. On the other hand, if I add a
1024
keyword parameter to branch.commit which is a *required* transaction
1025
object, I should rename the API - i.e. to 'branch.commit_transaction'.
1027
When renaming such supported API's, be sure to leave a deprecated_method (or
1028
_function or ...) behind which forwards to the new API. See the
1029
bzrlib.symbol_versioning module for decorators that take care of the
1030
details for you - such as updating the docstring, and issuing a warning
1031
when the old api is used.
1033
For unsupported API's, it does not hurt to follow this discipline, but it's
1034
not required. Minimally though, please try to rename things so that
1035
callers will at least get an AttributeError rather than weird results.
1038
Deprecation decorators
1039
----------------------
1041
``bzrlib.symbol_versioning`` provides decorators that can be attached to
1042
methods, functions, and other interfaces to indicate that they should no
1043
longer be used. For example::
1045
@deprecated_method(deprecated_in((0, 1, 4)))
1047
return self._new_foo()
1049
To deprecate a static method you must call ``deprecated_function``
1050
(**not** method), after the staticmethod call::
1053
@deprecated_function(deprecated_in((0, 1, 4)))
1054
def create_repository(base, shared=False, format=None):
1056
When you deprecate an API, you should not just delete its tests, because
1057
then we might introduce bugs in them. If the API is still present at all,
1058
it should still work. The basic approach is to use
1059
``TestCase.applyDeprecated`` which in one step checks that the API gives
1060
the expected deprecation message, and also returns the real result from
1061
the method, so that tests can keep running.
1063
Deprecation warnings will be suppressed for final releases, but not for
1064
development versions or release candidates, or when running ``bzr
1065
selftest``. This gives developers information about whether their code is
1066
using deprecated functions, but avoids confusing users about things they
1073
Processing Command Lines
1074
------------------------
1076
bzrlib has a standard framework for parsing command lines and calling
1077
processing routines associated with various commands. See builtins.py
1078
for numerous examples.
1081
Standard Parameter Types
1082
------------------------
1084
There are some common requirements in the library: some parameters need to be
1085
unicode safe, some need byte strings, and so on. At the moment we have
1086
only codified one specific pattern: Parameters that need to be unicode
1087
should be checked via ``bzrlib.osutils.safe_unicode``. This will coerce the
1088
input into unicode in a consistent fashion, allowing trivial strings to be
1089
used for programmer convenience, but not performing unpredictably in the
1090
presence of different locales.
1096
(The strategy described here is what we want to get to, but it's not
1097
consistently followed in the code at the moment.)
1099
bzrlib is intended to be a generically reusable library. It shouldn't
1100
write messages to stdout or stderr, because some programs that use it
1101
might want to display that information through a GUI or some other
1104
We can distinguish two types of output from the library:
1106
1. Structured data representing the progress or result of an
1107
operation. For example, for a commit command this will be a list
1108
of the modified files and the finally committed revision number
1111
These should be exposed either through the return code or by calls
1112
to a callback parameter.
1114
A special case of this is progress indicators for long-lived
1115
operations, where the caller should pass a ProgressBar object.
1117
2. Unstructured log/debug messages, mostly for the benefit of the
1118
developers or users trying to debug problems. This should always
1119
be sent through ``bzrlib.trace`` and Python ``logging``, so that
1120
it can be redirected by the client.
1122
The distinction between the two is a bit subjective, but in general if
1123
there is any chance that a library would want to see something as
1124
structured data, we should make it so.
1126
The policy about how output is presented in the text-mode client
1127
should be only in the command-line tool.
1134
Bazaar has online help for various topics through ``bzr help COMMAND`` or
1135
equivalently ``bzr command -h``. We also have help on command options,
1136
and on other help topics. (See ``help_topics.py``.)
1138
As for python docstrings, the first paragraph should be a single-sentence
1139
synopsis of the command.
1141
The help for options should be one or more proper sentences, starting with
1142
a capital letter and finishing with a full stop (period).
1144
All help messages and documentation should have two spaces between
1151
In general tests should be placed in a file named test_FOO.py where
1152
FOO is the logical thing under test. That file should be placed in the
1153
tests subdirectory under the package being tested.
1155
For example, tests for merge3 in bzrlib belong in bzrlib/tests/test_merge3.py.
1156
See bzrlib/tests/test_sampler.py for a template test script.
1158
Tests can be written for the UI or for individual areas of the library.
1159
Choose whichever is appropriate: if adding a new command, or a new command
1160
option, then you should be writing a UI test. If you are both adding UI
1161
functionality and library functionality, you will want to write tests for
1162
both the UI and the core behaviours. We call UI tests 'blackbox' tests
1163
and they are found in ``bzrlib/tests/blackbox/*.py``.
1165
When writing blackbox tests please honour the following conventions:
1167
1. Place the tests for the command 'name' in
1168
bzrlib/tests/blackbox/test_name.py. This makes it easy for developers
1169
to locate the test script for a faulty command.
1171
2. Use the 'self.run_bzr("name")' utility function to invoke the command
1172
rather than running bzr in a subprocess or invoking the
1173
cmd_object.run() method directly. This is a lot faster than
1174
subprocesses and generates the same logging output as running it in a
1175
subprocess (which invoking the method directly does not).
1177
3. Only test the one command in a single test script. Use the bzrlib
1178
library when setting up tests and when evaluating the side-effects of
1179
the command. We do this so that the library api has continual pressure
1180
on it to be as functional as the command line in a simple manner, and
1181
to isolate knock-on effects throughout the blackbox test suite when a
1182
command changes its name or signature. Ideally only the tests for a
1183
given command are affected when a given command is changed.
1185
4. If you have a test which does actually require running bzr in a
1186
subprocess you can use ``run_bzr_subprocess``. By default the spawned
1187
process will not load plugins unless ``--allow-plugins`` is supplied.
1193
We have a rich collection of tools to support writing tests. Please use
1194
them in preference to ad-hoc solutions as they provide portability and
1195
performance benefits.
1200
The ``TreeBuilder`` interface allows the construction of arbitrary trees
1201
with a declarative interface. A sample session might look like::
1203
tree = self.make_branch_and_tree('path')
1204
builder = TreeBuilder()
1205
builder.start_tree(tree)
1206
builder.build(['foo', "bar/", "bar/file"])
1207
tree.commit('commit the tree')
1208
builder.finish_tree()
1210
Please see bzrlib.treebuilder for more details.
1215
The ``BranchBuilder`` interface allows the creation of test branches in a
1216
quick and easy manner. A sample session::
1218
builder = BranchBuilder(self.get_transport().clone('relpath'))
1219
builder.build_commit()
1220
builder.build_commit()
1221
builder.build_commit()
1222
branch = builder.get_branch()
1224
Please see bzrlib.branchbuilder for more details.
1229
We make selective use of doctests__. In general they should provide
1230
*examples* within the API documentation which can incidentally be tested. We
1231
don't try to test every important case using doctests -- regular Python
1232
tests are generally a better solution.
1234
Most of these are in ``bzrlib/doc/api``. More additions are welcome.
1236
__ http://docs.python.org/lib/module-doctest.html
1241
Currently, bzr selftest is used to invoke tests.
1242
You can provide a pattern argument to run a subset. For example,
1243
to run just the blackbox tests, run::
1245
./bzr selftest -v blackbox
1247
To skip a particular test (or set of tests), use the --exclude option
1248
(shorthand -x) like so::
1250
./bzr selftest -v -x blackbox
1252
To list tests without running them, use the --list-only option like so::
1254
./bzr selftest --list-only
1256
This option can be combined with other selftest options (like -x) and
1257
filter patterns to understand their effect.
1260
Handling Errors and Exceptions
1261
==============================
1263
Commands should return non-zero when they encounter circumstances that
1264
the user should really pay attention to - which includes trivial shell
1267
Recommended values are:
1270
1. Conflicts in merge-like operations, or changes are present in
1271
diff-like operations.
1272
2. Unrepresentable diff changes (i.e. binary files that we cannot show
1274
3. An error or exception has occurred.
1275
4. An internal error occurred (one that shows a traceback.)
1277
Errors are handled through Python exceptions. Exceptions should be defined
1278
inside bzrlib.errors, so that we can see the whole tree at a glance.
1280
We broadly classify errors as either being either internal or not,
1281
depending on whether ``internal_error`` is set or not. If we think it's our
1282
fault, we show a backtrace, an invitation to report the bug, and possibly
1283
other details. This is the default for errors that aren't specifically
1284
recognized as being caused by a user error. Otherwise we show a briefer
1285
message, unless -Derror was given.
1287
Many errors originate as "environmental errors" which are raised by Python
1288
or builtin libraries -- for example IOError. These are treated as being
1289
our fault, unless they're caught in a particular tight scope where we know
1290
that they indicate a user errors. For example if the repository format
1291
is not found, the user probably gave the wrong path or URL. But if one of
1292
the files inside the repository is not found, then it's our fault --
1293
either there's a bug in bzr, or something complicated has gone wrong in
1294
the environment that means one internal file was deleted.
1296
Many errors are defined in ``bzrlib/errors.py`` but it's OK for new errors
1297
to be added near the place where they are used.
1299
Exceptions are formatted for the user by conversion to a string
1300
(eventually calling their ``__str__`` method.) As a convenience the
1301
``._fmt`` member can be used as a template which will be mapped to the
1302
error's instance dict.
1304
New exception classes should be defined when callers might want to catch
1305
that exception specifically, or when it needs a substantially different
1308
Exception strings should start with a capital letter and should not have a
1309
final fullstop. If long, they may contain newlines to break the text.
1315
Do not use the Python ``assert`` statement, either in tests or elsewhere.
1316
A source test checks that it is not used. It is ok to explicitly raise
1321
* It makes the behaviour vary depending on whether bzr is run with -O
1322
or not, therefore giving a chance for bugs that occur in one case or
1323
the other, several of which have already occurred: assertions with
1324
side effects, code which can't continue unless the assertion passes,
1325
cases where we should give the user a proper message rather than an
1327
* It's not that much shorter than an explicit if/raise.
1328
* It tends to lead to fuzzy thinking about whether the check is
1329
actually needed or not, and whether it's an internal error or not
1330
* It tends to cause look-before-you-leap patterns.
1331
* It's unsafe if the check is needed to protect the integrity of the
1333
* It tends to give poor messages since the developer can get by with
1334
no explanatory text at all.
1335
* We can't rely on people always running with -O in normal use, so we
1336
can't use it for tests that are actually expensive.
1337
* Expensive checks that help developers are better turned on from the
1338
test suite or a -D flag.
1339
* If used instead of ``self.assert*()`` in tests it makes them falsely pass with -O.
1345
When you change bzrlib, please update the relevant documentation for the
1346
change you made: Changes to commands should update their help, and
1347
possibly end user tutorials; changes to the core library should be
1348
reflected in API documentation.
1353
If you make a user-visible change, please add a note to the NEWS file.
1354
The description should be written to make sense to someone who's just
1355
a user of bzr, not a developer: new functions or classes shouldn't be
1356
mentioned, but new commands, changes in behaviour or fixed nontrivial
1357
bugs should be listed. See the existing entries for an idea of what
1360
Within each release, entries in the news file should have the most
1361
user-visible changes first. So the order should be approximately:
1363
* changes to existing behaviour - the highest priority because the
1364
user's existing knowledge is incorrect
1365
* new features - should be brought to their attention
1366
* bug fixes - may be of interest if the bug was affecting them, and
1367
should include the bug number if any
1368
* major documentation changes
1369
* changes to internal interfaces
1371
People who made significant contributions to each change are listed in
1372
parenthesis. This can include reporting bugs (particularly with good
1373
details or reproduction recipes), submitting patches, etc.
1378
The docstring of a command is used by ``bzr help`` to generate help output
1379
for the command. The list 'takes_options' attribute on a command is used by
1380
``bzr help`` to document the options for the command - the command
1381
docstring does not need to document them. Finally, the '_see_also'
1382
attribute on a command can be used to reference other related help topics.
1387
Functions, methods, classes and modules should have docstrings
1388
describing how they are used.
1390
The first line of the docstring should be a self-contained sentence.
1392
For the special case of Command classes, this acts as the user-visible
1393
documentation shown by the help command.
1395
The docstrings should be formatted as reStructuredText_ (like this
1396
document), suitable for processing using the epydoc_ tool into HTML
1399
.. _reStructuredText: http://docutils.sourceforge.net/rst.html
1400
.. _epydoc: http://epydoc.sourceforge.net/
1409
The copyright policy for bzr was recently made clear in this email (edited
1410
for grammatical correctness)::
1412
The attached patch cleans up the copyright and license statements in
1413
the bzr source. It also adds tests to help us remember to add them
1414
with the correct text.
1416
We had the problem that lots of our files were "Copyright Canonical
1417
Development Ltd" which is not a real company, and some other variations
1418
on this theme. Also, some files were missing the GPL statements.
1420
I want to be clear about the intent of this patch, since copyright can
1421
be a little controversial.
1423
1) The big motivation for this is not to shut out the community, but
1424
just to clean up all of the invalid copyright statements.
1426
2) It has been the general policy for bzr that we want a single
1427
copyright holder for all of the core code. This is following the model
1428
set by the FSF, which makes it easier to update the code to a new
1429
license in case problems are encountered. (For example, if we want to
1430
upgrade the project universally to GPL v3 it is much simpler if there is
1431
a single copyright holder). It also makes it clearer if copyright is
1432
ever debated, there is a single holder, which makes it easier to defend
1433
in court, etc. (I think the FSF position is that if you assign them
1434
copyright, they can defend it in court rather than you needing to, and
1435
I'm sure Canonical would do the same).
1436
As such, Canonical has requested copyright assignments from all of the
1439
3) If someone wants to add code and not attribute it to Canonical, there
1440
is a specific list of files that are excluded from this check. And the
1441
test failure indicates where that is, and how to update it.
1443
4) If anyone feels that I changed a copyright statement incorrectly, just
1444
let me know, and I'll be happy to correct it. Whenever you have large
1445
mechanical changes like this, it is possible to make some mistakes.
1447
Just to reiterate, this is a community project, and it is meant to stay
1448
that way. Core bzr code is copyright Canonical for legal reasons, and
1449
the tests are just there to help us maintain that.
1452
Miscellaneous Topics
1453
####################
1458
Bazaar has a few facilities to help debug problems by going into pdb_, the
1461
.. _pdb: http://docs.python.org/lib/debugger-commands.html
1463
If the ``BZR_PDB`` environment variable is set
1464
then bzr will go into pdb post-mortem mode when an unhandled exception
1467
If you send a SIGQUIT signal to bzr, which can be done by pressing
1468
Ctrl-\\ on Unix, bzr will go into the debugger immediately. You can
1469
continue execution by typing ``c``. This can be disabled if necessary
1470
by setting the environment variable ``BZR_SIGQUIT_PDB=0``.
1477
Integer identifier for a revision on the main line of a branch.
1478
Revision 0 is always the null revision; others are 1-based
1479
indexes into the branch's revision history.
1482
Unicode and Encoding Support
1483
============================
1485
This section discusses various techniques that Bazaar uses to handle
1486
characters that are outside the ASCII set.
1491
When a ``Command`` object is created, it is given a member variable
1492
accessible by ``self.outf``. This is a file-like object, which is bound to
1493
``sys.stdout``, and should be used to write information to the screen,
1494
rather than directly writing to ``sys.stdout`` or calling ``print``.
1495
This file has the ability to translate Unicode objects into the correct
1496
representation, based on the console encoding. Also, the class attribute
1497
``encoding_type`` will effect how unprintable characters will be
1498
handled. This parameter can take one of 3 values:
1501
Unprintable characters will be represented with a suitable replacement
1502
marker (typically '?'), and no exception will be raised. This is for
1503
any command which generates text for the user to review, rather than
1504
for automated processing.
1505
For example: ``bzr log`` should not fail if one of the entries has text
1506
that cannot be displayed.
1509
Attempting to print an unprintable character will cause a UnicodeError.
1510
This is for commands that are intended more as scripting support, rather
1511
than plain user review.
1512
For exampl: ``bzr ls`` is designed to be used with shell scripting. One
1513
use would be ``bzr ls --null --unknows | xargs -0 rm``. If ``bzr``
1514
printed a filename with a '?', the wrong file could be deleted. (At the
1515
very least, the correct file would not be deleted). An error is used to
1516
indicate that the requested action could not be performed.
1519
Do not attempt to automatically convert Unicode strings. This is used
1520
for commands that must handle conversion themselves.
1521
For example: ``bzr diff`` needs to translate Unicode paths, but should
1522
not change the exact text of the contents of the files.
1525
``bzrlib.urlutils.unescape_for_display``
1526
----------------------------------------
1528
Because Transports work in URLs (as defined earlier), printing the raw URL
1529
to the user is usually less than optimal. Characters outside the standard
1530
set are printed as escapes, rather than the real character, and local
1531
paths would be printed as ``file://`` urls. The function
1532
``unescape_for_display`` attempts to unescape a URL, such that anything
1533
that cannot be printed in the current encoding stays an escaped URL, but
1534
valid characters are generated where possible.
1540
The ``bzrlib.osutils`` module has many useful helper functions, including
1541
some more portable variants of functions in the standard library.
1543
In particular, don't use ``shutil.rmtree`` unless it's acceptable for it
1544
to fail on Windows if some files are readonly or still open elsewhere.
1545
Use ``bzrlib.osutils.rmtree`` instead.
1551
We write some extensions in C using pyrex. We design these to work in
1554
* User with no C compiler
1555
* User with C compiler
1558
The recommended way to install bzr is to have a C compiler so that the
1559
extensions can be built, but if no C compiler is present, the pure python
1560
versions we supply will work, though more slowly.
1562
For developers we recommend that pyrex be installed, so that the C
1563
extensions can be changed if needed.
1565
For the C extensions, the extension module should always match the
1566
original python one in all respects (modulo speed). This should be
1567
maintained over time.
1569
To create an extension, add rules to setup.py for building it with pyrex,
1570
and with distutils. Now start with an empty .pyx file. At the top add
1571
"include 'yourmodule.py'". This will import the contents of foo.py into this
1572
file at build time - remember that only one module will be loaded at
1573
runtime. Now you can subclass classes, or replace functions, and only your
1574
changes need to be present in the .pyx file.
1576
Note that pyrex does not support all 2.4 programming idioms, so some
1577
syntax changes may be required. I.e.
1579
- 'from foo import (bar, gam)' needs to change to not use the brackets.
1580
- 'import foo.bar as bar' needs to be 'import foo.bar; bar = foo.bar'
1582
If the changes are too dramatic, consider
1583
maintaining the python code twice - once in the .pyx, and once in the .py,
1584
and no longer including the .py file.
1587
Making Installers for OS Windows
1588
================================
1589
To build a win32 installer, see the instructions on the wiki page:
1590
http://bazaar-vcs.org/BzrWin32Installer
1593
Core Developer Tasks
1594
####################
1599
What is a Core Developer?
1600
-------------------------
1602
While everyone in the Bazaar community is welcome and encouraged to
1603
propose and submit changes, a smaller team is reponsible for pulling those
1604
changes together into a cohesive whole. In addition to the general developer
1605
stuff covered above, "core" developers have responsibility for:
1608
* reviewing blueprints
1610
* managing releases (see the `Releasing Bazaar <../../developers/releasing.html>`_)
1613
Removing barriers to community participation is a key reason for adopting
1614
distributed VCS technology. While DVCS removes many technical barriers,
1615
a small number of social barriers are often necessary instead.
1616
By documenting how the above things are done, we hope to
1617
encourage more people to participate in these activities, keeping the
1618
differences between core and non-core contributors to a minimum.
1621
Communicating and Coordinating
1622
------------------------------
1624
While it has many advantages, one of the challenges of distributed
1625
development is keeping everyone else aware of what you're working on.
1626
There are numerous ways to do this:
1628
#. Assign bugs to yourself in Launchpad
1629
#. Mention it on the mailing list
1630
#. Mention it on IRC
1632
As well as the email notifcations that occur when merge requests are sent
1633
and reviewed, you can keep others informed of where you're spending your
1634
energy by emailing the **bazaar-commits** list implicitly. To do this,
1635
install and configure the Email plugin. One way to do this is add these
1636
configuration settings to your central configuration file (e.g.
1637
``~/.bazaar/bazaar.conf`` on Linux)::
1640
email = Joe Smith <joe.smith@internode.on.net>
1641
smtp_server = mail.internode.on.net:25
1643
Then add these lines for the relevant branches in ``locations.conf``::
1645
post_commit_to = bazaar-commits@lists.canonical.com
1646
post_commit_mailer = smtplib
1648
While attending a sprint, RobertCollins' Dbus plugin is useful for the
1649
same reason. See the documentation within the plugin for information on
1650
how to set it up and configure it.
1656
Setting Up Your Workspace for Reviews
1657
-------------------------------------
1659
TODO: Incorporate John Arbash Meinel's detailed email to Ian C on the
1660
numerous ways of setting up integration branches.
1663
The Review Checklist
1664
--------------------
1666
See `A Closer Look at the Merge & Review Process`_
1667
for information on the gates used to decide whether code can be merged
1668
or not and details on how review results are recorded and communicated.
1671
The Importance of Timely Reviews
1672
--------------------------------
1674
Good reviews do take time. They also regularly require a solid
1675
understanding of the overall code base. In practice, this means a small
1676
number of people often have a large review burden - with knowledge comes
1677
responsibility. No one like their merge requests sitting in a queue going
1678
nowhere, so reviewing sooner rather than later is strongly encouraged.
1687
Of the many workflows supported by Bazaar, the one adopted for Bazaar
1688
development itself is known as "Decentralized with automatic gatekeeper".
1689
To repeat the explanation of this given on
1690
http://bazaar-vcs.org/Workflows:
1693
In this workflow, each developer has their own branch or
1694
branches, plus read-only access to the mainline. A software gatekeeper
1695
(e.g. PQM) has commit rights to the main branch. When a developer wants
1696
their work merged, they request the gatekeeper to merge it. The gatekeeper
1697
does a merge, a compile, and runs the test suite. If the code passes, it
1698
is merged into the mainline.
1700
In a nutshell, here's the overall submission process:
1702
#. get your work ready (including review except for trivial changes)
1703
#. push to a public location
1704
#. ask PQM to merge from that location
1707
At present, PQM always takes the changes to merge from a branch
1708
at a URL that can be read by it. For Bazaar, that means a public,
1709
typically http, URL.
1711
As a result, the following things are needed to use PQM for submissions:
1713
#. A publicly available web server
1714
#. Your OpenPGP key registered with PQM (contact RobertCollins for this)
1715
#. The PQM plugin installed and configured (not strictly required but
1716
highly recommended).
1719
Selecting a Public Branch Location
1720
----------------------------------
1722
If you don't have your own web server running, branches can always be
1723
pushed to Launchpad. Here's the process for doing that:
1725
Depending on your location throughout the world and the size of your
1726
repository though, it is often quicker to use an alternative public
1727
location to Launchpad, particularly if you can set up your own repo and
1728
push into that. By using an existing repo, push only needs to send the
1729
changes, instead of the complete repository every time. Note that it is
1730
easy to register branches in other locations with Launchpad so no benefits
1731
are lost by going this way.
1734
For Canonical staff, http://people.ubuntu.com/~<user>/ is one
1735
suggestion for public http branches. Contact your manager for information
1736
on accessing this system if required.
1738
It should also be noted that best practice in this area is subject to
1739
change as things evolve. For example, once the Bazaar smart server on
1740
Launchpad supports server-side branching, the performance situation will
1741
be very different to what it is now (Jun 2007).
1744
Configuring the PQM Plug-In
1745
---------------------------
1747
While not strictly required, the PQM plugin automates a few things and
1748
reduces the chance of error. Before looking at the plugin, it helps to
1749
understand a little more how PQM operates. Basically, PQM requires an
1750
email indicating what you want it to do. The email typically looks like
1753
star-merge source-branch target-branch
1757
star-merge http://bzr.arbash-meinel.com/branches/bzr/jam-integration http://bazaar-vcs.org/bzr/bzr.dev
1759
Note that the command needs to be on one line. The subject of the email
1760
will be used for the commit message. The email also needs to be ``gpg``
1761
signed with a key that PQM accepts.
1763
The advantages of using the PQM plugin are:
1765
#. You can use the config policies to make it easy to set up public
1766
branches, so you don't have to ever type the full paths you want to merge
1769
#. It checks to make sure the public branch last revision matches the
1770
local last revision so you are submitting what you think you are.
1772
#. It uses the same public_branch and smtp sending settings as bzr-email,
1773
so if you have one set up, you have the other mostly set up.
1775
#. Thunderbird refuses to not wrap lines, and request lines are usually
1776
pretty long (you have 2 long URLs in there).
1778
Here are sample configuration settings for the PQM plugin. Here are the
1779
lines in bazaar.conf::
1782
email = Joe Smith <joe.smith@internode.on.net>
1783
smtp_server=mail.internode.on.net:25
1785
And here are the lines in ``locations.conf`` (or ``branch.conf`` for
1786
dirstate-tags branches)::
1788
[/home/joe/bzr/my-integration]
1789
push_location = sftp://joe-smith@bazaar.launchpad.net/%7Ejoe-smith/bzr/my-integration/
1790
push_location:policy = norecurse
1791
public_branch = http://bazaar.launchpad.net/~joe-smith/bzr/my-integration/
1792
public_branch:policy = appendpath
1793
pqm_email = Bazaar PQM <pqm@bazaar-vcs.org>
1794
pqm_branch = http://bazaar-vcs.org/bzr/bzr.dev
1796
Note that the push settings will be added by the first ``push`` on
1797
a branch. Indeed the preferred way to generate the lines above is to use
1798
``push`` with an argument, then copy-and-paste the other lines into
1805
Here is one possible recipe once the above environment is set up:
1807
#. pull bzr.dev => my-integration
1808
#. merge patch => my-integration
1809
#. fix up any final merge conflicts (NEWS being the big killer here).
1815
The ``push`` step is not required if ``my-integration`` is a checkout of
1818
Because of defaults, you can type a single message into commit and
1819
pqm-commit will reuse that.
1822
Tracking Change Acceptance
1823
--------------------------
1825
The web interface to PQM is https://pqm.bazaar-vcs.org/. After submitting
1826
a change, you can visit this URL to confirm it was received and placed in
1829
When PQM completes processing a change, an email is sent to you with the
1833
Reviewing Blueprints
1834
====================
1836
Blueprint Tracking Using Launchpad
1837
----------------------------------
1839
New features typically require a fair amount of discussion, design and
1840
debate. For Bazaar, that information is often captured in a so-called
1841
"blueprint" on our Wiki. Overall tracking of blueprints and their status
1842
is done using Launchpad's relevant tracker,
1843
https://blueprints.launchpad.net/bzr/. Once a blueprint for ready for
1844
review, please announce it on the mailing list.
1846
Alternatively, send an email begining with [RFC] with the proposal to the
1847
list. In some cases, you may wish to attach proposed code or a proposed
1848
developer document if that best communicates the idea. Debate can then
1849
proceed using the normal merge review processes.
1852
Recording Blueprint Review Feedback
1853
-----------------------------------
1855
Unlike its Bug Tracker, Launchpad's Blueprint Tracker doesn't currently
1856
(Jun 2007) support a chronological list of comment responses. Review
1857
feedback can either be recorded on the Wiki hosting the blueprints or by
1858
using Launchpad's whiteboard feature.
1867
As the two senior developers, Martin Pool and Robert Collins coordinate
1868
the overall Bazaar product development roadmap. Core developers provide
1869
input and review into this, particularly during sprints. It's totally
1870
expected that community members ought to be working on things that
1871
interest them the most. The roadmap is valuable though because it provides
1872
context for understanding where the product is going as a whole and why.
1875
Using Releases and Milestones in Launchpad
1876
------------------------------------------
1878
TODO ... (Exact policies still under discussion)
1884
Keeping on top of bugs reported is an important part of ongoing release
1885
planning. Everyone in the community is welcome and encouraged to raise
1886
bugs, confirm bugs raised by others, and nominate a priority. Practically
1887
though, a good percentage of bug triage is often done by the core
1888
developers, partially because of their depth of product knowledge.
1890
With respect to bug triage, core developers are encouraged to play an
1891
active role with particular attention to the following tasks:
1893
* keeping the number of unconfirmed bugs low
1894
* ensuring the priorities are generally right (everything as critical - or
1895
medium - is meaningless)
1896
* looking out for regressions and turning those around sooner rather than later.
1899
As well as prioritizing bugs and nominating them against a
1900
target milestone, Launchpad lets core developers offer to mentor others in
1905
vim: ft=rst tw=74 ai
added
removed
doc/developers/HACKING.txt
