1
============================
2
Guidelines for modifying bzr
3
============================
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>`_.
7
(The current version of this document is available in the file ``HACKING``
8
in the source tree, or at http://bazaar-ng.org/hacking.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:
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* Launchpad - https://launchpad.net/
102
* Bazaar - http://bazaar-vcs.org/
104
* Bundle Buggy - http://bundlebuggy.aaronbentley.com/
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* Patch Queue Manager - https://launchpad.net/pqm/
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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::
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bzr merge-directive http://bazaar-vcs.org http://example.org/my_branch > my_directive.patch
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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
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to be merged, you can put '[RFC]' in the subject line.
139
Anyone is welcome to review code. There are broadly three gates for
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* 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.
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* 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
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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.
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:approve: Reviewer wants this submission merged.
165
:tweak: Reviewer wants this submission merged with small changes. (No
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:abstain: Reviewer does not intend to vote on this patch.
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:resubmit: Please make changes and resubmit for review.
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:reject: Reviewer doesn't want this kind of change merged.
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:comment: Not really a vote. Reviewer just wants to comment, for now.
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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
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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
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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
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<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:
13
283
* New functionality should have test cases. Preferably write the
14
284
test before writing the code.
16
286
In general, you can test at either the command-line level or the
17
internal API level. See Writing Tests below for more detail.
287
internal API level. See Writing tests below for more detail.
19
* Try to practice Test-Driven Development. before fixing a bug, write a
289
* Try to practice Test-Driven Development: before fixing a bug, write a
20
290
test case so that it does not regress. Similarly for adding a new
21
291
feature: write a test case for a small version of the new feature before
22
292
starting on the code itself. Check the test fails on the old code, then
23
293
add the feature or fix and check it passes.
25
* Exceptions should be defined inside bzrlib.errors, so that we can
26
see the whole tree at a glance.
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
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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
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can help in some cases (like running only the failed tests for some time)::
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./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
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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
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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
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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.
409
When writing library functionality, it is often necessary to set up a
410
branch with a certain history. Most current tests do this by inheriting
411
from ``TestCaseWithTransport`` and using the ``make_branch_and_tree``
412
helper to give them a ``WorkingTree`` that they can commit to. However,
413
there is a newer api available from ``TestCaseWithMemoryTransport`` using
414
the ``make_branch_builder`` helper. This helper is preferred, because it
415
can build the changes in memory, rather than on disk. Tests that are
416
explictly testing how we work with disk objects should, of course, use a
417
real ``WorkingTree``. See ``bzrlib/branch_builder.py`` for how to use the
424
We make selective use of doctests__. In general they should provide
425
*examples* within the API documentation which can incidentally be tested. We
426
don't try to test every important case using doctests -- regular Python
427
tests are generally a better solution.
429
Most of these are in ``bzrlib/doc/api``. More additions are welcome.
431
__ http://docs.python.org/lib/module-doctest.html
434
Skipping tests and test requirements
435
------------------------------------
437
In our enhancements to unittest we allow for some addition results beyond
438
just success or failure.
440
If a test can't be run, it can say that it's skipped. This is typically
441
used in parameterized tests - for example if a transport doesn't support
442
setting permissions, we'll skip the tests that relating to that. ::
445
return self.branch_format.initialize(repo.bzrdir)
446
except errors.UninitializableFormat:
447
raise tests.TestSkipped('Uninitializable branch format')
449
Raising TestSkipped is a good idea when you want to make it clear that the
450
test was not run, rather than just returning which makes it look as if it
453
Several different cases are distinguished:
456
Generic skip; the only type that was present up to bzr 0.18.
459
The test doesn't apply to the parameters with which it was run.
460
This is typically used when the test is being applied to all
461
implementations of an interface, but some aspects of the interface
462
are optional and not present in particular concrete
463
implementations. (Some tests that should raise this currently
464
either silently return or raise TestSkipped.) Another option is
465
to use more precise parameterization to avoid generating the test
469
**(Not implemented yet)**
470
The test can't be run because of an inherent limitation of the
471
environment, such as not having symlinks or not supporting
475
The test can't be run because a dependency (typically a Python
476
library) is not available in the test environment. These
477
are in general things that the person running the test could fix
478
by installing the library. It's OK if some of these occur when
479
an end user runs the tests or if we're specifically testing in a
480
limited environment, but a full test should never see them.
483
The test exists but is known to fail, for example because the
484
code to fix it hasn't been run yet. Raising this allows
485
you to distinguish these failures from the ones that are not
486
expected to fail. This could be conditionally raised if something
487
is broken on some platforms but not on others.
489
If the test would fail because of something we don't expect or
490
intend to fix, KnownFailure is not appropriate, and
491
TestNotApplicable might be better.
493
We plan to support three modes for running the test suite to control the
494
interpretation of these results. Strict mode is for use in situations
495
like merges to the mainline and releases where we want to make sure that
496
everything that can be tested has been tested. Lax mode is for use by
497
developers who want to temporarily tolerate some known failures. The
498
default behaviour is obtained by ``bzr selftest`` with no options, and
499
also (if possible) by running under another unittest harness.
501
======================= ======= ======= ========
502
result strict default lax
503
======================= ======= ======= ========
504
TestSkipped pass pass pass
505
TestNotApplicable pass pass pass
506
TestPlatformLimit pass pass pass
507
TestDependencyMissing fail pass pass
508
KnownFailure fail pass pass
509
======================= ======= ======= ========
512
Test feature dependencies
513
-------------------------
515
Rather than manually checking the environment in each test, a test class
516
can declare its dependence on some test features. The feature objects are
517
checked only once for each run of the whole test suite.
519
For historical reasons, as of May 2007 many cases that should depend on
520
features currently raise TestSkipped.)
524
class TestStrace(TestCaseWithTransport):
526
_test_needs_features = [StraceFeature]
528
This means all tests in this class need the feature. The feature itself
529
should provide a ``_probe`` method which is called once to determine if
532
These should generally be equivalent to either TestDependencyMissing or
533
sometimes TestPlatformLimit.
539
Known failures are when a test exists but we know it currently doesn't
540
work, allowing the test suite to still pass. These should be used with
541
care, we don't want a proliferation of quietly broken tests. It might be
542
appropriate to use them if you've committed a test for a bug but not the
543
fix for it, or if something works on Unix but not on Windows.
546
Testing exceptions and errors
547
-----------------------------
549
It's important to test handling of errors and exceptions. Because this
550
code is often not hit in ad-hoc testing it can often have hidden bugs --
551
it's particularly common to get NameError because the exception code
552
references a variable that has since been renamed.
554
.. TODO: Something about how to provoke errors in the right way?
556
In general we want to test errors at two levels:
558
1. A test in ``test_errors.py`` checking that when the exception object is
559
constructed with known parameters it produces an expected string form.
560
This guards against mistakes in writing the format string, or in the
561
``str`` representations of its parameters. There should be one for
562
each exception class.
564
2. Tests that when an api is called in a particular situation, it raises
565
an error of the expected class. You should typically use
566
``assertRaises``, which in the Bazaar test suite returns the exception
567
object to allow you to examine its parameters.
569
In some cases blackbox tests will also want to check error reporting. But
570
it can be difficult to provoke every error through the commandline
571
interface, so those tests are only done as needed -- eg in response to a
572
particular bug or if the error is reported in an unusual way(?) Blackbox
573
tests should mostly be testing how the command-line interface works, so
574
should only test errors if there is something particular to the cli in how
575
they're displayed or handled.
581
The Python ``warnings`` module is used to indicate a non-fatal code
582
problem. Code that's expected to raise a warning can be tested through
585
The test suite can be run with ``-Werror`` to check no unexpected errors
588
However, warnings should be used with discretion. It's not an appropriate
589
way to give messages to the user, because the warning is normally shown
590
only once per source line that causes the problem. You should also think
591
about whether the warning is serious enought that it should be visible to
592
users who may not be able to fix it.
595
Interface implementation testing and test scenarios
596
---------------------------------------------------
598
There are several cases in Bazaar of multiple implementations of a common
599
conceptual interface. ("Conceptual" because
600
it's not necessary for all the implementations to share a base class,
601
though they often do.) Examples include transports and the working tree,
602
branch and repository classes.
604
In these cases we want to make sure that every implementation correctly
605
fulfils the interface requirements. For example, every Transport should
606
support the ``has()`` and ``get()`` and ``clone()`` methods. We have a
607
sub-suite of tests in ``test_transport_implementations``. (Most
608
per-implementation tests are in submodules of ``bzrlib.tests``, but not
609
the transport tests at the moment.)
611
These tests are repeated for each registered Transport, by generating a
612
new TestCase instance for the cross product of test methods and transport
613
implementations. As each test runs, it has ``transport_class`` and
614
``transport_server`` set to the class it should test. Most tests don't
615
access these directly, but rather use ``self.get_transport`` which returns
616
a transport of the appropriate type.
618
The goal is to run per-implementation only tests that relate to that
619
particular interface. Sometimes we discover a bug elsewhere that happens
620
with only one particular transport. Once it's isolated, we can consider
621
whether a test should be added for that particular implementation,
622
or for all implementations of the interface.
624
The multiplication of tests for different implementations is normally
625
accomplished by overriding the ``test_suite`` function used to load
626
tests from a module. This function typically loads all the tests,
627
then applies a TestProviderAdapter to them, which generates a longer
628
suite containing all the test variations.
634
Some utilities are provided for generating variations of tests. This can
635
be used for per-implementation tests, or other cases where the same test
636
code needs to run several times on different scenarios.
638
The general approach is to define a class that provides test methods,
639
which depend on attributes of the test object being pre-set with the
640
values to which the test should be applied. The test suite should then
641
also provide a list of scenarios in which to run the tests.
643
Typically ``multiply_tests_from_modules`` should be called from the test
644
module's ``test_suite`` function.
647
Essential Domain Classes
648
########################
650
Introducing the Object Model
651
============================
653
The core domain objects within the bazaar model are:
663
Transports are explained below. See http://bazaar-vcs.org/Classes/
664
for an introduction to the other key classes.
669
The ``Transport`` layer handles access to local or remote directories.
670
Each Transport object acts like a logical connection to a particular
671
directory, and it allows various operations on files within it. You can
672
*clone* a transport to get a new Transport connected to a subdirectory or
675
Transports are not used for access to the working tree. At present
676
working trees are always local and they are accessed through the regular
677
Python file io mechanisms.
682
Transports work in URLs. Take note that URLs are by definition only
683
ASCII - the decision of how to encode a Unicode string into a URL must be
684
taken at a higher level, typically in the Store. (Note that Stores also
685
escape filenames which cannot be safely stored on all filesystems, but
686
this is a different level.)
688
The main reason for this is that it's not possible to safely roundtrip a
689
URL into Unicode and then back into the same URL. The URL standard
690
gives a way to represent non-ASCII bytes in ASCII (as %-escapes), but
691
doesn't say how those bytes represent non-ASCII characters. (They're not
692
guaranteed to be UTF-8 -- that is common but doesn't happen everywhere.)
694
For example if the user enters the url ``http://example/%e0`` there's no
695
way to tell whether that character represents "latin small letter a with
696
grave" in iso-8859-1, or "latin small letter r with acute" in iso-8859-2
697
or malformed UTF-8. So we can't convert their URL to Unicode reliably.
699
Equally problematic if we're given a url-like string containing non-ascii
700
characters (such as the accented a) we can't be sure how to convert that
701
to the correct URL, because we don't know what encoding the server expects
702
for those characters. (Although this is not totally reliable we might still
703
accept these and assume they should be put into UTF-8.)
705
A similar edge case is that the url ``http://foo/sweet%2Fsour`` contains
706
one directory component whose name is "sweet/sour". The escaped slash is
707
not a directory separator. If we try to convert URLs to regular Unicode
708
paths this information will be lost.
710
This implies that Transports must natively deal with URLs; for simplicity
711
they *only* deal with URLs and conversion of other strings to URLs is done
712
elsewhere. Information they return, such as from ``list_dir``, is also in
713
the form of URL components.
716
Coding Style Guidelines
717
#######################
722
``hasattr`` should not be used because it swallows exceptions including
723
``KeyboardInterrupt``. Instead, say something like ::
725
if getattr(thing, 'name', None) is None
731
Please write PEP-8__ compliant code.
733
__ http://www.python.org/peps/pep-0008.html
735
One often-missed requirement is that the first line of docstrings
736
should be a self-contained one-sentence summary.
738
We use 4 space indents for blocks, and never use tab characters. (In vim,
741
Lines should be no more than 79 characters if at all possible.
742
Lines that continue a long statement may be indented in either of
745
within the parenthesis or other character that opens the block, e.g.::
751
or indented by four spaces::
757
The first is considered clearer by some people; however it can be a bit
758
harder to maintain (e.g. when the method name changes), and it does not
759
work well if the relevant parenthesis is already far to the right. Avoid
762
self.legbone.kneebone.shinbone.toebone.shake_it(one,
768
self.legbone.kneebone.shinbone.toebone.shake_it(one,
774
self.legbone.kneebone.shinbone.toebone.shake_it(
777
For long lists, we like to add a trailing comma and put the closing
778
character on the following line. This makes it easier to add new items in
781
from bzrlib.goo import (
787
There should be spaces between function paramaters, but not between the
788
keyword name and the value::
790
call(1, 3, cheese=quark)
794
;(defface my-invalid-face
795
; '((t (:background "Red" :underline t)))
796
; "Face used to highlight invalid constructs or other uglyties"
799
(defun my-python-mode-hook ()
800
;; setup preferred indentation style.
801
(setq fill-column 79)
802
(setq indent-tabs-mode nil) ; no tabs, never, I will not repeat
803
; (font-lock-add-keywords 'python-mode
804
; '(("^\\s *\t" . 'my-invalid-face) ; Leading tabs
805
; ("[ \t]+$" . 'my-invalid-face) ; Trailing spaces
806
; ("^[ \t]+$" . 'my-invalid-face)); Spaces only
810
(add-hook 'python-mode-hook 'my-python-mode-hook)
812
The lines beginning with ';' are comments. They can be activated
813
if one want to have a strong notice of some tab/space usage
28
820
* Imports should be done at the top-level of the file, unless there is
29
821
a strong reason to have them lazily loaded when a particular
209
897
> factory, then yes, foo_factory is what I would use.
903
Several places in Bazaar use (or will use) a registry, which is a
904
mapping from names to objects or classes. The registry allows for
905
loading in registered code only when it's needed, and keeping
906
associated information such as a help string or description.
909
InterObject and multiple dispatch
910
=================================
912
The ``InterObject`` provides for two-way `multiple dispatch`__: matching
913
up for example a source and destination repository to find the right way
914
to transfer data between them.
916
.. __: http://en.wikipedia.org/wiki/Multiple_dispatch
918
There is a subclass ``InterObject`` classes for each type of object that is
919
dispatched this way, e.g. ``InterRepository``. Calling ``.get()`` on this
920
class will return an ``InterObject`` instance providing the best match for
921
those parameters, and this instance then has methods for operations
924
inter = InterRepository.get(source_repo, target_repo)
925
inter.fetch(revision_id)
927
``InterRepository`` also acts as a registry-like object for its
928
subclasses, and they can be added through ``.register_optimizer``. The
929
right one to run is selected by asking each class, in reverse order of
930
registration, whether it ``.is_compatible`` with the relevant objects.
935
To make startup time faster, we use the ``bzrlib.lazy_import`` module to
936
delay importing modules until they are actually used. ``lazy_import`` uses
937
the same syntax as regular python imports. So to import a few modules in a
940
from bzrlib.lazy_import import lazy_import
941
lazy_import(globals(), """
950
revision as _mod_revision,
952
import bzrlib.transport
956
At this point, all of these exist as a ``ImportReplacer`` object, ready to
957
be imported once a member is accessed. Also, when importing a module into
958
the local namespace, which is likely to clash with variable names, it is
959
recommended to prefix it as ``_mod_<module>``. This makes it clearer that
960
the variable is a module, and these object should be hidden anyway, since
961
they shouldn't be imported into other namespaces.
963
While it is possible for ``lazy_import()`` to import members of a module
964
when using the ``from module import member`` syntax, it is recommended to
965
only use that syntax to load sub modules ``from module import submodule``.
966
This is because variables and classes can frequently be used without
967
needing a sub-member for example::
969
lazy_import(globals(), """
970
from module import MyClass
974
return isinstance(x, MyClass)
976
This will incorrectly fail, because ``MyClass`` is a ``ImportReplacer``
977
object, rather than the real class.
979
It also is incorrect to assign ``ImportReplacer`` objects to other variables.
980
Because the replacer only knows about the original name, it is unable to
981
replace other variables. The ``ImportReplacer`` class will raise an
982
``IllegalUseOfScopeReplacer`` exception if it can figure out that this
983
happened. But it requires accessing a member more than once from the new
984
variable, so some bugs are not detected right away.
990
The null revision is the ancestor of all revisions. Its revno is 0, its
991
revision-id is ``null:``, and its tree is the empty tree. When referring
992
to the null revision, please use ``bzrlib.revision.NULL_REVISION``. Old
993
code sometimes uses ``None`` for the null revision, but this practice is
997
Object string representations
998
=============================
1000
Python prints objects using their ``__repr__`` method when they are
1001
written to logs, exception tracebacks, or the debugger. We want
1002
objects to have useful representations to help in determining what went
1005
If you add a new class you should generally add a ``__repr__`` method
1006
unless there is an adequate method in a parent class. There should be a
1009
Representations should typically look like Python constructor syntax, but
1010
they don't need to include every value in the object and they don't need
1011
to be able to actually execute. They're to be read by humans, not
1012
machines. Don't hardcode the classname in the format, so that we get the
1013
correct value if the method is inherited by a subclass. If you're
1014
printing attributes of the object, including strings, you should normally
1015
use ``%r`` syntax (to call their repr in turn).
1017
Try to avoid the representation becoming more than one or two lines long.
1018
(But balance this against including useful information, and simplicity of
1021
Because repr methods are often called when something has already gone
1022
wrong, they should be written somewhat more defensively than most code.
1023
The object may be half-initialized or in some other way in an illegal
1024
state. The repr method shouldn't raise an exception, or it may hide the
1025
(probably more useful) underlying exception.
1030
return '%s(%r)' % (self.__class__.__name__,
1037
A bare ``except`` statement will catch all exceptions, including ones that
1038
really should terminate the program such as ``MemoryError`` and
1039
``KeyboardInterrupt``. They should rarely be used unless the exception is
1040
later re-raised. Even then, think about whether catching just
1041
``Exception`` (which excludes system errors in Python2.5 and later) would
1052
We have a commitment to 6 months API stability - any supported symbol in a
1053
release of bzr MUST NOT be altered in any way that would result in
1054
breaking existing code that uses it. That means that method names,
1055
parameter ordering, parameter names, variable and attribute names etc must
1056
not be changed without leaving a 'deprecated forwarder' behind. This even
1057
applies to modules and classes.
1059
If you wish to change the behaviour of a supported API in an incompatible
1060
way, you need to change its name as well. For instance, if I add an optional keyword
1061
parameter to branch.commit - that's fine. On the other hand, if I add a
1062
keyword parameter to branch.commit which is a *required* transaction
1063
object, I should rename the API - i.e. to 'branch.commit_transaction'.
1065
When renaming such supported API's, be sure to leave a deprecated_method (or
1066
_function or ...) behind which forwards to the new API. See the
1067
bzrlib.symbol_versioning module for decorators that take care of the
1068
details for you - such as updating the docstring, and issuing a warning
1069
when the old api is used.
1071
For unsupported API's, it does not hurt to follow this discipline, but it's
1072
not required. Minimally though, please try to rename things so that
1073
callers will at least get an AttributeError rather than weird results.
1076
Deprecation decorators
1077
----------------------
1079
``bzrlib.symbol_versioning`` provides decorators that can be attached to
1080
methods, functions, and other interfaces to indicate that they should no
1081
longer be used. For example::
1083
@deprecated_method(deprecated_in((0, 1, 4)))
1085
return self._new_foo()
1087
To deprecate a static method you must call ``deprecated_function``
1088
(**not** method), after the staticmethod call::
1091
@deprecated_function(deprecated_in((0, 1, 4)))
1092
def create_repository(base, shared=False, format=None):
1094
When you deprecate an API, you should not just delete its tests, because
1095
then we might introduce bugs in them. If the API is still present at all,
1096
it should still work. The basic approach is to use
1097
``TestCase.applyDeprecated`` which in one step checks that the API gives
1098
the expected deprecation message, and also returns the real result from
1099
the method, so that tests can keep running.
1101
Deprecation warnings will be suppressed for final releases, but not for
1102
development versions or release candidates, or when running ``bzr
1103
selftest``. This gives developers information about whether their code is
1104
using deprecated functions, but avoids confusing users about things they
1111
Processing Command Lines
1112
------------------------
1114
bzrlib has a standard framework for parsing command lines and calling
1115
processing routines associated with various commands. See builtins.py
1116
for numerous examples.
1119
Standard Parameter Types
1120
------------------------
1122
There are some common requirements in the library: some parameters need to be
1123
unicode safe, some need byte strings, and so on. At the moment we have
1124
only codified one specific pattern: Parameters that need to be unicode
1125
should be checked via ``bzrlib.osutils.safe_unicode``. This will coerce the
1126
input into unicode in a consistent fashion, allowing trivial strings to be
1127
used for programmer convenience, but not performing unpredictably in the
1128
presence of different locales.
215
1134
(The strategy described here is what we want to get to, but it's not
291
1283
./bzr selftest -v blackbox
294
Errors and exceptions
295
=====================
297
Errors are handled through Python exceptions. They can represent user
298
errors, environmental errors or program bugs. Sometimes we can't be sure
299
at the time it's raised which case applies. See bzrlib/errors.py for
300
details on the error-handling practices.
1285
To skip a particular test (or set of tests), use the --exclude option
1286
(shorthand -x) like so::
1288
./bzr selftest -v -x blackbox
1290
To list tests without running them, use the --list-only option like so::
1292
./bzr selftest --list-only
1294
This option can be combined with other selftest options (like -x) and
1295
filter patterns to understand their effect.
1298
Handling Errors and Exceptions
1299
==============================
1301
Commands should return non-zero when they encounter circumstances that
1302
the user should really pay attention to - which includes trivial shell
1305
Recommended values are:
1308
1. Conflicts in merge-like operations, or changes are present in
1309
diff-like operations.
1310
2. Unrepresentable diff changes (i.e. binary files that we cannot show
1312
3. An error or exception has occurred.
1313
4. An internal error occurred (one that shows a traceback.)
1315
Errors are handled through Python exceptions. Exceptions should be defined
1316
inside bzrlib.errors, so that we can see the whole tree at a glance.
1318
We broadly classify errors as either being either internal or not,
1319
depending on whether ``internal_error`` is set or not. If we think it's our
1320
fault, we show a backtrace, an invitation to report the bug, and possibly
1321
other details. This is the default for errors that aren't specifically
1322
recognized as being caused by a user error. Otherwise we show a briefer
1323
message, unless -Derror was given.
1325
Many errors originate as "environmental errors" which are raised by Python
1326
or builtin libraries -- for example IOError. These are treated as being
1327
our fault, unless they're caught in a particular tight scope where we know
1328
that they indicate a user errors. For example if the repository format
1329
is not found, the user probably gave the wrong path or URL. But if one of
1330
the files inside the repository is not found, then it's our fault --
1331
either there's a bug in bzr, or something complicated has gone wrong in
1332
the environment that means one internal file was deleted.
1334
Many errors are defined in ``bzrlib/errors.py`` but it's OK for new errors
1335
to be added near the place where they are used.
1337
Exceptions are formatted for the user by conversion to a string
1338
(eventually calling their ``__str__`` method.) As a convenience the
1339
``._fmt`` member can be used as a template which will be mapped to the
1340
error's instance dict.
1342
New exception classes should be defined when callers might want to catch
1343
that exception specifically, or when it needs a substantially different
1346
Exception strings should start with a capital letter and should not have a
1347
final fullstop. If long, they may contain newlines to break the text.
1353
Do not use the Python ``assert`` statement, either in tests or elsewhere.
1354
A source test checks that it is not used. It is ok to explicitly raise
1359
* It makes the behaviour vary depending on whether bzr is run with -O
1360
or not, therefore giving a chance for bugs that occur in one case or
1361
the other, several of which have already occurred: assertions with
1362
side effects, code which can't continue unless the assertion passes,
1363
cases where we should give the user a proper message rather than an
1365
* It's not that much shorter than an explicit if/raise.
1366
* It tends to lead to fuzzy thinking about whether the check is
1367
actually needed or not, and whether it's an internal error or not
1368
* It tends to cause look-before-you-leap patterns.
1369
* It's unsafe if the check is needed to protect the integrity of the
1371
* It tends to give poor messages since the developer can get by with
1372
no explanatory text at all.
1373
* We can't rely on people always running with -O in normal use, so we
1374
can't use it for tests that are actually expensive.
1375
* Expensive checks that help developers are better turned on from the
1376
test suite or a -D flag.
1377
* If used instead of ``self.assert*()`` in tests it makes them falsely pass with -O.
1383
When you change bzrlib, please update the relevant documentation for the
1384
change you made: Changes to commands should update their help, and
1385
possibly end user tutorials; changes to the core library should be
1386
reflected in API documentation.
1391
If you make a user-visible change, please add a note to the NEWS file.
1392
The description should be written to make sense to someone who's just
1393
a user of bzr, not a developer: new functions or classes shouldn't be
1394
mentioned, but new commands, changes in behaviour or fixed nontrivial
1395
bugs should be listed. See the existing entries for an idea of what
1398
Within each release, entries in the news file should have the most
1399
user-visible changes first. So the order should be approximately:
1401
* changes to existing behaviour - the highest priority because the
1402
user's existing knowledge is incorrect
1403
* new features - should be brought to their attention
1404
* bug fixes - may be of interest if the bug was affecting them, and
1405
should include the bug number if any
1406
* major documentation changes
1407
* changes to internal interfaces
1409
People who made significant contributions to each change are listed in
1410
parenthesis. This can include reporting bugs (particularly with good
1411
details or reproduction recipes), submitting patches, etc.
1416
The docstring of a command is used by ``bzr help`` to generate help output
1417
for the command. The list 'takes_options' attribute on a command is used by
1418
``bzr help`` to document the options for the command - the command
1419
docstring does not need to document them. Finally, the '_see_also'
1420
attribute on a command can be used to reference other related help topics.
1425
Functions, methods, classes and modules should have docstrings
1426
describing how they are used.
1428
The first line of the docstring should be a self-contained sentence.
1430
For the special case of Command classes, this acts as the user-visible
1431
documentation shown by the help command.
1433
The docstrings should be formatted as reStructuredText_ (like this
1434
document), suitable for processing using the epydoc_ tool into HTML
1437
.. _reStructuredText: http://docutils.sourceforge.net/rst.html
1438
.. _epydoc: http://epydoc.sourceforge.net/
1447
The copyright policy for bzr was recently made clear in this email (edited
1448
for grammatical correctness)::
1450
The attached patch cleans up the copyright and license statements in
1451
the bzr source. It also adds tests to help us remember to add them
1452
with the correct text.
1454
We had the problem that lots of our files were "Copyright Canonical
1455
Development Ltd" which is not a real company, and some other variations
1456
on this theme. Also, some files were missing the GPL statements.
1458
I want to be clear about the intent of this patch, since copyright can
1459
be a little controversial.
1461
1) The big motivation for this is not to shut out the community, but
1462
just to clean up all of the invalid copyright statements.
1464
2) It has been the general policy for bzr that we want a single
1465
copyright holder for all of the core code. This is following the model
1466
set by the FSF, which makes it easier to update the code to a new
1467
license in case problems are encountered. (For example, if we want to
1468
upgrade the project universally to GPL v3 it is much simpler if there is
1469
a single copyright holder). It also makes it clearer if copyright is
1470
ever debated, there is a single holder, which makes it easier to defend
1471
in court, etc. (I think the FSF position is that if you assign them
1472
copyright, they can defend it in court rather than you needing to, and
1473
I'm sure Canonical would do the same).
1474
As such, Canonical has requested copyright assignments from all of the
1477
3) If someone wants to add code and not attribute it to Canonical, there
1478
is a specific list of files that are excluded from this check. And the
1479
test failure indicates where that is, and how to update it.
1481
4) If anyone feels that I changed a copyright statement incorrectly, just
1482
let me know, and I'll be happy to correct it. Whenever you have large
1483
mechanical changes like this, it is possible to make some mistakes.
1485
Just to reiterate, this is a community project, and it is meant to stay
1486
that way. Core bzr code is copyright Canonical for legal reasons, and
1487
the tests are just there to help us maintain that.
1490
Miscellaneous Topics
1491
####################
1496
Bazaar has a few facilities to help debug problems by going into pdb_, the
1499
.. _pdb: http://docs.python.org/lib/debugger-commands.html
1501
If the ``BZR_PDB`` environment variable is set
1502
then bzr will go into pdb post-mortem mode when an unhandled exception
1505
If you send a SIGQUIT signal to bzr, which can be done by pressing
1506
Ctrl-\\ on Unix, bzr will go into the debugger immediately. You can
1507
continue execution by typing ``c``. This can be disabled if necessary
1508
by setting the environment variable ``BZR_SIGQUIT_PDB=0``.
309
1517
indexes into the branch's revision history.
315
The ``Transport`` layer handles access to local or remote directories.
316
Each Transport object acts like a logical connection to a particular
317
directory, and it allows various operations on files within it. You can
318
*clone* a transport to get a new Transport connected to a subdirectory or
321
Transports are not used for access to the working tree. At present
322
working trees are always local and they are accessed through the regular
323
Python file io mechanisms.
328
Transports work in URLs. Take note that URLs are by definition only
329
ASCII - the decision of how to encode a Unicode string into a URL must be
330
taken at a higher level, typically in the Store. (Note that Stores also
331
escape filenames which cannot be safely stored on all filesystems, but
332
this is a different level.)
334
The main reason for this is that it's not possible to safely roundtrip a
335
URL into Unicode and then back into the same URL. The URL standard
336
gives a way to represent non-ASCII bytes in ASCII (as %-escapes), but
337
doesn't say how those bytes represent non-ASCII characters. (They're not
338
guaranteed to be UTF-8 -- that is common but doesn't happen everywhere.)
340
For example if the user enters the url ``http://example/%e0`` there's no
341
way to tell whether that character represents "latin small letter a with
342
grave" in iso-8859-1, or "latin small letter r with acute" in iso-8859-2
343
or malformed UTF-8. So we can't convert their URL to Unicode reliably.
345
Equally problematic if we're given a url-like string containing non-ascii
346
characters (such as the accented a) we can't be sure how to convert that
347
to the correct URL, because we don't know what encoding the server expects
348
for those characters. (Although this is not totally reliable we might still
349
accept these and assume they should be put into UTF-8.)
351
A similar edge case is that the url ``http://foo/sweet%2Fsour" contains
352
one directory component whose name is "sweet/sour". The escaped slash is
353
not a directory separator. If we try to convert URLs to regular Unicode
354
paths this information will be lost.
356
This implies that Transports must natively deal with URLs; for simplicity
357
they *only* deal with URLs and conversion of other strings to URLs is done
358
elsewhere. Information they return, such as from ``list_dir``, is also in
359
the form of URL components.
1520
Unicode and Encoding Support
1521
============================
1523
This section discusses various techniques that Bazaar uses to handle
1524
characters that are outside the ASCII set.
1529
When a ``Command`` object is created, it is given a member variable
1530
accessible by ``self.outf``. This is a file-like object, which is bound to
1531
``sys.stdout``, and should be used to write information to the screen,
1532
rather than directly writing to ``sys.stdout`` or calling ``print``.
1533
This file has the ability to translate Unicode objects into the correct
1534
representation, based on the console encoding. Also, the class attribute
1535
``encoding_type`` will effect how unprintable characters will be
1536
handled. This parameter can take one of 3 values:
1539
Unprintable characters will be represented with a suitable replacement
1540
marker (typically '?'), and no exception will be raised. This is for
1541
any command which generates text for the user to review, rather than
1542
for automated processing.
1543
For example: ``bzr log`` should not fail if one of the entries has text
1544
that cannot be displayed.
1547
Attempting to print an unprintable character will cause a UnicodeError.
1548
This is for commands that are intended more as scripting support, rather
1549
than plain user review.
1550
For exampl: ``bzr ls`` is designed to be used with shell scripting. One
1551
use would be ``bzr ls --null --unknows | xargs -0 rm``. If ``bzr``
1552
printed a filename with a '?', the wrong file could be deleted. (At the
1553
very least, the correct file would not be deleted). An error is used to
1554
indicate that the requested action could not be performed.
1557
Do not attempt to automatically convert Unicode strings. This is used
1558
for commands that must handle conversion themselves.
1559
For example: ``bzr diff`` needs to translate Unicode paths, but should
1560
not change the exact text of the contents of the files.
1563
``bzrlib.urlutils.unescape_for_display``
1564
----------------------------------------
1566
Because Transports work in URLs (as defined earlier), printing the raw URL
1567
to the user is usually less than optimal. Characters outside the standard
1568
set are printed as escapes, rather than the real character, and local
1569
paths would be printed as ``file://`` urls. The function
1570
``unescape_for_display`` attempts to unescape a URL, such that anything
1571
that cannot be printed in the current encoding stays an escaped URL, but
1572
valid characters are generated where possible.
1578
The ``bzrlib.osutils`` module has many useful helper functions, including
1579
some more portable variants of functions in the standard library.
1581
In particular, don't use ``shutil.rmtree`` unless it's acceptable for it
1582
to fail on Windows if some files are readonly or still open elsewhere.
1583
Use ``bzrlib.osutils.rmtree`` instead.
1589
We write some extensions in C using pyrex. We design these to work in
1592
* User with no C compiler
1593
* User with C compiler
1596
The recommended way to install bzr is to have a C compiler so that the
1597
extensions can be built, but if no C compiler is present, the pure python
1598
versions we supply will work, though more slowly.
1600
For developers we recommend that pyrex be installed, so that the C
1601
extensions can be changed if needed.
1603
For the C extensions, the extension module should always match the
1604
original python one in all respects (modulo speed). This should be
1605
maintained over time.
1607
To create an extension, add rules to setup.py for building it with pyrex,
1608
and with distutils. Now start with an empty .pyx file. At the top add
1609
"include 'yourmodule.py'". This will import the contents of foo.py into this
1610
file at build time - remember that only one module will be loaded at
1611
runtime. Now you can subclass classes, or replace functions, and only your
1612
changes need to be present in the .pyx file.
1614
Note that pyrex does not support all 2.4 programming idioms, so some
1615
syntax changes may be required. I.e.
1617
- 'from foo import (bar, gam)' needs to change to not use the brackets.
1618
- 'import foo.bar as bar' needs to be 'import foo.bar; bar = foo.bar'
1620
If the changes are too dramatic, consider
1621
maintaining the python code twice - once in the .pyx, and once in the .py,
1622
and no longer including the .py file.
1625
Making Installers for OS Windows
1626
================================
1627
To build a win32 installer, see the instructions on the wiki page:
1628
http://bazaar-vcs.org/BzrWin32Installer
1631
Core Developer Tasks
1632
####################
1637
What is a Core Developer?
1638
-------------------------
1640
While everyone in the Bazaar community is welcome and encouraged to
1641
propose and submit changes, a smaller team is reponsible for pulling those
1642
changes together into a cohesive whole. In addition to the general developer
1643
stuff covered above, "core" developers have responsibility for:
1646
* reviewing blueprints
1648
* managing releases (see the `Releasing Bazaar <../../developers/releasing.html>`_)
1651
Removing barriers to community participation is a key reason for adopting
1652
distributed VCS technology. While DVCS removes many technical barriers,
1653
a small number of social barriers are often necessary instead.
1654
By documenting how the above things are done, we hope to
1655
encourage more people to participate in these activities, keeping the
1656
differences between core and non-core contributors to a minimum.
1659
Communicating and Coordinating
1660
------------------------------
1662
While it has many advantages, one of the challenges of distributed
1663
development is keeping everyone else aware of what you're working on.
1664
There are numerous ways to do this:
1666
#. Assign bugs to yourself in Launchpad
1667
#. Mention it on the mailing list
1668
#. Mention it on IRC
1670
As well as the email notifcations that occur when merge requests are sent
1671
and reviewed, you can keep others informed of where you're spending your
1672
energy by emailing the **bazaar-commits** list implicitly. To do this,
1673
install and configure the Email plugin. One way to do this is add these
1674
configuration settings to your central configuration file (e.g.
1675
``~/.bazaar/bazaar.conf`` on Linux)::
1678
email = Joe Smith <joe.smith@internode.on.net>
1679
smtp_server = mail.internode.on.net:25
1681
Then add these lines for the relevant branches in ``locations.conf``::
1683
post_commit_to = bazaar-commits@lists.canonical.com
1684
post_commit_mailer = smtplib
1686
While attending a sprint, RobertCollins' Dbus plugin is useful for the
1687
same reason. See the documentation within the plugin for information on
1688
how to set it up and configure it.
1694
Setting Up Your Workspace for Reviews
1695
-------------------------------------
1697
TODO: Incorporate John Arbash Meinel's detailed email to Ian C on the
1698
numerous ways of setting up integration branches.
1701
The Review Checklist
1702
--------------------
1704
See `A Closer Look at the Merge & Review Process`_
1705
for information on the gates used to decide whether code can be merged
1706
or not and details on how review results are recorded and communicated.
1709
The Importance of Timely Reviews
1710
--------------------------------
1712
Good reviews do take time. They also regularly require a solid
1713
understanding of the overall code base. In practice, this means a small
1714
number of people often have a large review burden - with knowledge comes
1715
responsibility. No one like their merge requests sitting in a queue going
1716
nowhere, so reviewing sooner rather than later is strongly encouraged.
1725
Of the many workflows supported by Bazaar, the one adopted for Bazaar
1726
development itself is known as "Decentralized with automatic gatekeeper".
1727
To repeat the explanation of this given on
1728
http://bazaar-vcs.org/Workflows:
1731
In this workflow, each developer has their own branch or
1732
branches, plus read-only access to the mainline. A software gatekeeper
1733
(e.g. PQM) has commit rights to the main branch. When a developer wants
1734
their work merged, they request the gatekeeper to merge it. The gatekeeper
1735
does a merge, a compile, and runs the test suite. If the code passes, it
1736
is merged into the mainline.
1738
In a nutshell, here's the overall submission process:
1740
#. get your work ready (including review except for trivial changes)
1741
#. push to a public location
1742
#. ask PQM to merge from that location
1745
At present, PQM always takes the changes to merge from a branch
1746
at a URL that can be read by it. For Bazaar, that means a public,
1747
typically http, URL.
1749
As a result, the following things are needed to use PQM for submissions:
1751
#. A publicly available web server
1752
#. Your OpenPGP key registered with PQM (contact RobertCollins for this)
1753
#. The PQM plugin installed and configured (not strictly required but
1754
highly recommended).
1757
Selecting a Public Branch Location
1758
----------------------------------
1760
If you don't have your own web server running, branches can always be
1761
pushed to Launchpad. Here's the process for doing that:
1763
Depending on your location throughout the world and the size of your
1764
repository though, it is often quicker to use an alternative public
1765
location to Launchpad, particularly if you can set up your own repo and
1766
push into that. By using an existing repo, push only needs to send the
1767
changes, instead of the complete repository every time. Note that it is
1768
easy to register branches in other locations with Launchpad so no benefits
1769
are lost by going this way.
1772
For Canonical staff, http://people.ubuntu.com/~<user>/ is one
1773
suggestion for public http branches. Contact your manager for information
1774
on accessing this system if required.
1776
It should also be noted that best practice in this area is subject to
1777
change as things evolve. For example, once the Bazaar smart server on
1778
Launchpad supports server-side branching, the performance situation will
1779
be very different to what it is now (Jun 2007).
1782
Configuring the PQM Plug-In
1783
---------------------------
1785
While not strictly required, the PQM plugin automates a few things and
1786
reduces the chance of error. Before looking at the plugin, it helps to
1787
understand a little more how PQM operates. Basically, PQM requires an
1788
email indicating what you want it to do. The email typically looks like
1791
star-merge source-branch target-branch
1795
star-merge http://bzr.arbash-meinel.com/branches/bzr/jam-integration http://bazaar-vcs.org/bzr/bzr.dev
1797
Note that the command needs to be on one line. The subject of the email
1798
will be used for the commit message. The email also needs to be ``gpg``
1799
signed with a key that PQM accepts.
1801
The advantages of using the PQM plugin are:
1803
#. You can use the config policies to make it easy to set up public
1804
branches, so you don't have to ever type the full paths you want to merge
1807
#. It checks to make sure the public branch last revision matches the
1808
local last revision so you are submitting what you think you are.
1810
#. It uses the same public_branch and smtp sending settings as bzr-email,
1811
so if you have one set up, you have the other mostly set up.
1813
#. Thunderbird refuses to not wrap lines, and request lines are usually
1814
pretty long (you have 2 long URLs in there).
1816
Here are sample configuration settings for the PQM plugin. Here are the
1817
lines in bazaar.conf::
1820
email = Joe Smith <joe.smith@internode.on.net>
1821
smtp_server=mail.internode.on.net:25
1823
And here are the lines in ``locations.conf`` (or ``branch.conf`` for
1824
dirstate-tags branches)::
1826
[/home/joe/bzr/my-integration]
1827
push_location = sftp://joe-smith@bazaar.launchpad.net/%7Ejoe-smith/bzr/my-integration/
1828
push_location:policy = norecurse
1829
public_branch = http://bazaar.launchpad.net/~joe-smith/bzr/my-integration/
1830
public_branch:policy = appendpath
1831
pqm_email = Bazaar PQM <pqm@bazaar-vcs.org>
1832
pqm_branch = http://bazaar-vcs.org/bzr/bzr.dev
1834
Note that the push settings will be added by the first ``push`` on
1835
a branch. Indeed the preferred way to generate the lines above is to use
1836
``push`` with an argument, then copy-and-paste the other lines into
1843
Here is one possible recipe once the above environment is set up:
1845
#. pull bzr.dev => my-integration
1846
#. merge patch => my-integration
1847
#. fix up any final merge conflicts (NEWS being the big killer here).
1853
The ``push`` step is not required if ``my-integration`` is a checkout of
1856
Because of defaults, you can type a single message into commit and
1857
pqm-commit will reuse that.
1860
Tracking Change Acceptance
1861
--------------------------
1863
The web interface to PQM is https://pqm.bazaar-vcs.org/. After submitting
1864
a change, you can visit this URL to confirm it was received and placed in
1867
When PQM completes processing a change, an email is sent to you with the
1871
Reviewing Blueprints
363
1872
====================
365
If you'd like to propose a change, please post to the
366
bazaar-ng@lists.canonical.com list with a patch, bzr changeset, or link to a
367
branch. Please put '[patch]' in the subject so we can pick them out, and
368
include some text explaining the change. Remember to put an update to the NEWS
369
file in your diff, if it makes any changes visible to users or plugin
370
developers. Please include a diff against mainline if you're giving a link to
373
Please indicate if you think the code is ready to merge, or if it's just a
374
draft or for discussion. If you want comments from many developers rather than
375
to be merged, you can put '[rfc]' in the subject lines.
377
Anyone is welcome to review code. There are broadly three gates for
380
* Doesn't reduce test coverage: if it adds new methods or commands,
381
there should be tests for them. There is a good test framework
382
and plenty of examples to crib from, but if you are having trouble
383
working out how to test something feel free to post a draft patch
386
* Doesn't reduce design clarity, such as by entangling objects
387
we're trying to separate. This is mostly something the more
388
experienced reviewers need to help check.
390
* Improves bugs, features, speed, or code simplicity.
392
Code that goes in should pass all three.
394
If you read a patch please reply and say so. We can use a numeric scale
395
of -1, -0, +0, +1, meaning respectively "really don't want it in current
396
form", "somewhat uncomfortable", "ok with me", and "please put it in".
397
Anyone can "vote". (It's not really voting, just a terse expression.)
399
If something gets say two +1 votes from core reviewers, and no
400
vetos, then it's OK to come in. Any of the core developers can bring it
401
into their integration branch, which I'll merge regularly. (If you do
402
so, please reply and say so.)
1874
Blueprint Tracking Using Launchpad
1875
----------------------------------
1877
New features typically require a fair amount of discussion, design and
1878
debate. For Bazaar, that information is often captured in a so-called
1879
"blueprint" on our Wiki. Overall tracking of blueprints and their status
1880
is done using Launchpad's relevant tracker,
1881
https://blueprints.launchpad.net/bzr/. Once a blueprint for ready for
1882
review, please announce it on the mailing list.
1884
Alternatively, send an email begining with [RFC] with the proposal to the
1885
list. In some cases, you may wish to attach proposed code or a proposed
1886
developer document if that best communicates the idea. Debate can then
1887
proceed using the normal merge review processes.
1890
Recording Blueprint Review Feedback
1891
-----------------------------------
1893
Unlike its Bug Tracker, Launchpad's Blueprint Tracker doesn't currently
1894
(Jun 2007) support a chronological list of comment responses. Review
1895
feedback can either be recorded on the Wiki hosting the blueprints or by
1896
using Launchpad's whiteboard feature.
1905
As the two senior developers, Martin Pool and Robert Collins coordinate
1906
the overall Bazaar product development roadmap. Core developers provide
1907
input and review into this, particularly during sprints. It's totally
1908
expected that community members ought to be working on things that
1909
interest them the most. The roadmap is valuable though because it provides
1910
context for understanding where the product is going as a whole and why.
1913
Using Releases and Milestones in Launchpad
1914
------------------------------------------
1916
TODO ... (Exact policies still under discussion)
1922
Keeping on top of bugs reported is an important part of ongoing release
1923
planning. Everyone in the community is welcome and encouraged to raise
1924
bugs, confirm bugs raised by others, and nominate a priority. Practically
1925
though, a good percentage of bug triage is often done by the core
1926
developers, partially because of their depth of product knowledge.
1928
With respect to bug triage, core developers are encouraged to play an
1929
active role with particular attention to the following tasks:
1931
* keeping the number of unconfirmed bugs low
1932
* ensuring the priorities are generally right (everything as critical - or
1933
medium - is meaningless)
1934
* looking out for regressions and turning those around sooner rather than later.
1937
As well as prioritizing bugs and nominating them against a
1938
target milestone, Launchpad lets core developers offer to mentor others in
1943
vim: ft=rst tw=74 ai
added
removed
doc/developers/HACKING.txt
