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 latest developer documentation can be found online at
15
http://doc.bazaar-vcs.org/developers/.
21
Exploring the Bazaar Platform
22
=============================
24
Before making changes, it's a good idea to explore the work already
25
done by others. Perhaps the new feature or improvement you're looking
26
for is available in another plug-in already? If you find a bug,
27
perhaps someone else has already fixed it?
29
To answer these questions and more, take a moment to explore the
30
overall Bazaar Platform. Here are some links to browse:
32
* The Plugins page on the Wiki - http://bazaar-vcs.org/BzrPlugins
34
* The Bazaar product family on Launchpad - https://launchpad.net/bazaar
36
* Bug Tracker for the core product - https://bugs.launchpad.net/bzr/
38
* Blueprint Tracker for the core product - https://blueprints.launchpad.net/bzr/
40
If nothing else, perhaps you'll find inspiration in how other developers
41
have solved their challenges.
43
Finding Something To Do
44
=======================
46
Ad-hoc performance work can also be done. One useful tool is the 'evil' debug
47
flag. For instance running ``bzr -Devil commit -m "test"`` will log a backtrace
48
to the bzr log file for every method call which triggers a slow or non-scalable
49
part of the bzr library. So checking that a given command with ``-Devil`` has
50
no backtraces logged to the log file is a good way to find problem function
51
calls that might be nested deep in the code base.
53
Planning and Discussing Changes
54
===============================
56
There is a very active community around Bazaar. Mostly we meet on IRC
57
(#bzr on irc.freenode.net) and on the mailing list. To join the Bazaar
58
community, see http://bazaar-vcs.org/BzrSupport.
60
If you are planning to make a change, it's a very good idea to mention it
61
on the IRC channel and/or on the mailing list. There are many advantages
62
to involving the community before you spend much time on a change.
65
* you get to build on the wisdom of others, saving time
67
* if others can direct you to similar code, it minimises the work to be done
69
* it assists everyone in coordinating direction, priorities and effort.
71
In summary, maximising the input from others typically minimises the
72
total effort required to get your changes merged. The community is
73
friendly, helpful and always keen to welcome newcomers.
76
Bazaar Development in a Nutshell
77
================================
79
.. was from bazaar-vcs.org/BzrGivingBack
81
One of the fun things about working on a version control system like Bazaar is
82
that the users have a high level of proficiency in contributing back into
83
the tool. Consider the following very brief introduction to contributing back
84
to Bazaar. More detailed instructions are in the following sections.
89
First, get a local copy of the development mainline (See `Why make a local
95
$ bzr branch http://bazaar-vcs.org/bzr/bzr.dev/ bzr.dev
97
Now make your own branch::
99
$ bzr branch bzr.dev 123456-my-bugfix
101
This will give you a branch called "123456-my-bugfix" that you can work on
102
and commit in. Here, you can study the code, make a fix or a new feature.
103
Feel free to commit early and often (after all, it's your branch!).
105
Documentation improvements are an easy place to get started giving back to the
106
Bazaar project. The documentation is in the `doc/` subdirectory of the Bazaar
109
When you are done, make sure that you commit your last set of changes as well!
110
Once you are happy with your changes, ask for them to be merged, as described
113
Making a Merge Proposal
114
-----------------------
116
The Bazaar developers use Launchpad to further enable a truly distributed
117
style of development. Anyone can propose a branch for merging into the Bazaar
118
trunk. To start this process, you need to push your branch to Launchpad. To
119
do this, you will need a Launchpad account and user name, e.g.
120
`your_lp_username`. You can push your branch to Launchpad directly from
123
$ bzr push lp:~your_lp_username/bzr/giveback
125
After you have pushed your branch, you will need to propose it for merging to
126
the Bazaar trunk. Go to <https://launchpad.net/your_lp_username/bzr/giveback>
127
and choose "Propose for merging into another branch". Select "~bzr/bzr/trunk"
128
to hand your changes off to the Bazaar developers for review and merging.
130
Why make a local copy of bzr.dev?
131
---------------------------------
133
Making a local mirror of bzr.dev is not strictly necessary, but it means
135
- You can use that copy of bzr.dev as your main bzr executable, and keep it
136
up-to-date using ``bzr pull``.
137
- Certain operations are faster, and can be done when offline. For example:
140
- ``bzr diff -r ancestor:...``
143
- When it's time to create your next branch, it's more convenient. When you
144
have further contributions to make, you should do them in their own branch::
147
$ bzr branch bzr.dev additional_fixes
148
$ cd additional_fixes # hack, hack, hack
152
Understanding the Development Process
153
=====================================
155
The development team follows many practices including:
157
* a public roadmap and planning process in which anyone can participate
159
* time based milestones everyone can work towards and plan around
161
* extensive code review and feedback to contributors
163
* complete and rigorous test coverage on any code contributed
165
* automated validation that all tests still pass before code is merged
166
into the main code branch.
168
The key tools we use to enable these practices are:
170
* Launchpad - https://launchpad.net/
172
* Bazaar - http://bazaar-vcs.org/
174
* Bundle Buggy - http://bundlebuggy.aaronbentley.com/
176
* Patch Queue Manager - https://launchpad.net/pqm/
178
For further information, see http://bazaar-vcs.org/BzrDevelopment.
183
Preparing a Sandbox for Making Changes to Bazaar
184
================================================
186
Bazaar supports many ways of organising your work. See
187
http://bazaar-vcs.org/SharedRepositoryLayouts for a summary of the
188
popular alternatives.
190
Of course, the best choice for you will depend on numerous factors:
191
the number of changes you may be making, the complexity of the changes, etc.
192
As a starting suggestion though:
194
* create a local copy of the main development branch (bzr.dev) by using
197
bzr branch http://bazaar-vcs.org/bzr/bzr.dev/ bzr.dev
199
* keep your copy of bzr.dev pristine (by not developing in it) and keep
200
it up to date (by using bzr pull)
202
* create a new branch off your local bzr.dev copy for each issue
203
(bug or feature) you are working on.
205
This approach makes it easy to go back and make any required changes
206
after a code review. Resubmitting the change is then simple with no
207
risk of accidentally including edits related to other issues you may
208
be working on. After the changes for an issue are accepted and merged,
209
the associated branch can be deleted or archived as you wish.
212
Navigating the Code Base
213
========================
215
.. Was at <http://bazaar-vcs.org/NewDeveloperIntroduction>
217
Some of the key files in this directory are:
220
The command you run to start Bazaar itself. This script is pretty
221
short and just does some checks then jumps into bzrlib.
224
This file covers a brief introduction to Bazaar and lists some of its
228
Summary of changes in each Bazaar release that can affect users or
232
Installs Bazaar system-wide or to your home directory. To perform
233
development work on Bazaar it is not required to run this file - you
234
can simply run the bzr command from the top level directory of your
235
development copy. Note: That if you run setup.py this will create a
236
'build' directory in your development branch. There's nothing wrong
237
with this but don't be confused by it. The build process puts a copy
238
of the main code base into this build directory, along with some other
239
files. You don't need to go in here for anything discussed in this
243
Possibly the most exciting folder of all, bzrlib holds the main code
244
base. This is where you will go to edit python files and contribute to
248
Holds documentation on a whole range of things on Bazaar from the
249
origination of ideas within the project to information on Bazaar
250
features and use cases. Within this directory there is a subdirectory
251
for each translation into a human language. All the documentation
252
is in the ReStructuredText markup language.
255
Documentation specifically targeted at Bazaar and plugin developers.
256
(Including this document.)
260
Automatically-generated API reference information is available at
261
<http://starship.python.net/crew/mwh/bzrlibapi/>.
263
See also the `Bazaar Architectural Overview
264
<http://doc.bazaar-vcs.org/developers/overview.html>`_.
267
The Code Review Process
268
#######################
270
All code changes coming in to Bazaar are reviewed by someone else.
271
Normally changes by core contributors are reviewed by one other core
272
developer, and changes from other people are reviewed by two core
273
developers. Use intelligent discretion if the patch is trivial.
275
Good reviews do take time. They also regularly require a solid
276
understanding of the overall code base. In practice, this means a small
277
number of people often have a large review burden - with knowledge comes
278
responsibility. No one likes their merge requests sitting in a queue going
279
nowhere, so reviewing sooner rather than later is strongly encouraged.
288
Please put a "cover letter" on your merge request explaining:
290
* the reason **why** you're making this change
292
* **how** this change achieves this purpose
294
* anything else you may have fixed in passing
296
* anything significant that you thought of doing, such as a more
297
extensive fix or a different approach, but didn't or couldn't do now
299
A good cover letter makes reviewers' lives easier because they can decide
300
from the letter whether they agree with the purpose and approach, and then
301
assess whether the patch actually does what the cover letter says.
302
Explaining any "drive-by fixes" or roads not taken may also avoid queries
303
from the reviewer. All in all this should give faster and better reviews.
304
Sometimes writing the cover letter helps the submitter realize something
305
else they need to do. The size of the cover letter should be proportional
306
to the size and complexity of the patch.
309
Reviewing proposed changes
310
==========================
312
Anyone is welcome to review code, and reply to the thread with their
315
The simplest way to review a proposed change is to just read the patch on
316
the list or in Bundle Buggy. For more complex changes it may be useful
317
to make a new working tree or branch from trunk, and merge the proposed
318
change into it, so you can experiment with the code or look at a wider
321
There are three main requirements for code to get in:
323
* Doesn't reduce test coverage: if it adds new methods or commands,
324
there should be tests for them. There is a good test framework
325
and plenty of examples to crib from, but if you are having trouble
326
working out how to test something feel free to post a draft patch
329
* Doesn't reduce design clarity, such as by entangling objects
330
we're trying to separate. This is mostly something the more
331
experienced reviewers need to help check.
333
* Improves bugs, features, speed, or code simplicity.
335
Code that goes in should not degrade any of these aspects. Patches are
336
welcome that only cleanup the code without changing the external
337
behaviour. The core developers take care to keep the code quality high
338
and understandable while recognising that perfect is sometimes the enemy
341
It is easy for reviews to make people notice other things which should be
342
fixed but those things should not hold up the original fix being accepted.
343
New things can easily be recorded in the Bug Tracker instead.
345
It's normally much easier to review several smaller patches than one large
346
one. You might want to use ``bzr-loom`` to maintain threads of related
347
work, or submit a preparatory patch that will make your "real" change
351
Checklist for reviewers
352
=======================
354
* Do you understand what the code's doing and why?
356
* Will it perform reasonably for large inputs, both in memory size and
357
run time? Are there some scenarios where performance should be
360
* Is it tested, and are the tests at the right level? Are there both
361
blackbox (command-line level) and API-oriented tests?
363
* If this change will be visible to end users or API users, is it
364
appropriately documented in NEWS?
366
* Does it meet the coding standards below?
368
* If it changes the user-visible behaviour, does it update the help
369
strings and user documentation?
371
* If it adds a new major concept or standard practice, does it update the
372
developer documentation?
374
* (your ideas here...)
380
From May 2009 on, we prefer people to propose code reviews through
383
* <https://launchpad.net/+tour/code-review>
385
* <https://help.launchpad.net/Code/Review>
387
Anyone can propose or comment on a merge proposal just by creating a
390
There are two ways to create a new merge proposal: through the web
391
interface or by email.
394
Proposing a merge through the web
395
---------------------------------
397
To create the proposal through the web, first push your branch to Launchpad.
398
For example, a branch dealing with documentation belonging to the Launchpad
399
User mbp could be pushed as ::
401
bzr push lp:~mbp/bzr/doc
403
Then go to the branch's web page, which in this case would be
404
<https://code.launchpad.net/~mbp/bzr/doc>. You can simplify this step by just
409
You can then click "Propose for merging into another branch", and enter your
410
cover letter (see above) into the web form. Typically you'll want to merge
411
into ``~bzr/bzr/trunk`` which will be the default; you might also want to
412
nominate merging into a release branch for a bug fix. There is the option to
413
specify a specific reviewer or type of review, and you shouldn't normally
416
Submitting the form takes you to the new page about the merge proposal
417
containing the diff of the changes, comments by interested people, and
418
controls to comment or vote on the change.
420
Proposing a merge by mail
421
-------------------------
423
To propose a merge by mail, send a bundle to ``merge@code.launchpad.net``.
425
You can generate a merge request like this::
427
bzr send -o bug-1234.diff
429
``bzr send`` can also send mail directly if you prefer; see the help.
434
From <https://code.launchpad.net/bzr/+activereviews> you can see all
435
currently active reviews, and choose one to comment on. This page also
436
shows proposals that are now approved and should be merged by someone with
440
Reviews through Bundle Buggy
441
============================
443
The Bundle Buggy tool used up to May 2009 is still available as a review
446
Sending patches for review
447
--------------------------
449
If you'd like to propose a change, please post to the
450
bazaar@lists.canonical.com list with a bundle, patch, or link to a
451
branch. Put ``[PATCH]`` or ``[MERGE]`` in the subject so Bundle Buggy
452
can pick it out, and explain the change in the email message text.
453
Remember to update the NEWS file as part of your change if it makes any
454
changes visible to users or plugin developers. Please include a diff
455
against mainline if you're giving a link to a branch.
457
You can generate a merge request like this::
459
bzr send -o bug-1234.patch
461
A ``.patch`` extension is recommended instead of .bundle as many mail clients
462
will send the latter as a binary file.
464
``bzr send`` can also send mail directly if you prefer; see the help.
466
Please do **NOT** put [PATCH] or [MERGE] in the subject line if you don't
467
want it to be merged. If you want comments from developers rather than
468
to be merged, you can put ``[RFC]`` in the subject line.
470
If this change addresses a bug, please put the bug number in the subject
471
line too, in the form ``[#1]`` so that Bundle Buggy can recognize it.
473
If the change is intended for a particular release mark that in the
474
subject too, e.g. ``[1.6]``.
475
Anyone can "vote" on the mailing list by expressing an opinion. Core
476
developers can also vote using Bundle Buggy. Here are the voting codes and
479
:approve: Reviewer wants this submission merged.
480
:tweak: Reviewer wants this submission merged with small changes. (No
482
:abstain: Reviewer does not intend to vote on this patch.
483
:resubmit: Please make changes and resubmit for review.
484
:reject: Reviewer doesn't want this kind of change merged.
485
:comment: Not really a vote. Reviewer just wants to comment, for now.
487
If a change gets two approvals from core reviewers, and no rejections,
488
then it's OK to come in. Any of the core developers can bring it into the
489
bzr.dev trunk and backport it to maintenance branches if required. The
490
Release Manager will merge the change into the branch for a pending
491
release, if any. As a guideline, core developers usually merge their own
492
changes and volunteer to merge other contributions if they were the second
493
reviewer to agree to a change.
495
To track the progress of proposed changes, use Bundle Buggy. See
496
http://bundlebuggy.aaronbentley.com/help for a link to all the
497
outstanding merge requests together with an explanation of the columns.
498
Bundle Buggy will also mail you a link to track just your change.
500
Coding Style Guidelines
501
#######################
506
``hasattr`` should not be used because it swallows exceptions including
507
``KeyboardInterrupt``. Instead, say something like ::
509
if getattr(thing, 'name', None) is None
515
Please write PEP-8__ compliant code.
517
__ http://www.python.org/peps/pep-0008.html
519
One often-missed requirement is that the first line of docstrings
520
should be a self-contained one-sentence summary.
522
We use 4 space indents for blocks, and never use tab characters. (In vim,
525
Trailing white space should be avoided, but is allowed.
526
You should however not make lots of unrelated white space changes.
528
Unix style newlines (LF) are used.
530
Each file must have a newline at the end of it.
532
Lines should be no more than 79 characters if at all possible.
533
Lines that continue a long statement may be indented in either of
536
within the parenthesis or other character that opens the block, e.g.::
542
or indented by four spaces::
548
The first is considered clearer by some people; however it can be a bit
549
harder to maintain (e.g. when the method name changes), and it does not
550
work well if the relevant parenthesis is already far to the right. Avoid
553
self.legbone.kneebone.shinbone.toebone.shake_it(one,
559
self.legbone.kneebone.shinbone.toebone.shake_it(one,
565
self.legbone.kneebone.shinbone.toebone.shake_it(
568
For long lists, we like to add a trailing comma and put the closing
569
character on the following line. This makes it easier to add new items in
572
from bzrlib.goo import (
578
There should be spaces between function parameters, but not between the
579
keyword name and the value::
581
call(1, 3, cheese=quark)
585
;(defface my-invalid-face
586
; '((t (:background "Red" :underline t)))
587
; "Face used to highlight invalid constructs or other uglyties"
590
(defun my-python-mode-hook ()
591
;; setup preferred indentation style.
592
(setq fill-column 79)
593
(setq indent-tabs-mode nil) ; no tabs, never, I will not repeat
594
; (font-lock-add-keywords 'python-mode
595
; '(("^\\s *\t" . 'my-invalid-face) ; Leading tabs
596
; ("[ \t]+$" . 'my-invalid-face) ; Trailing spaces
597
; ("^[ \t]+$" . 'my-invalid-face)); Spaces only
601
(add-hook 'python-mode-hook 'my-python-mode-hook)
603
The lines beginning with ';' are comments. They can be activated
604
if one want to have a strong notice of some tab/space usage
1
============================
2
Guidelines for modifying bzr
3
============================
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)
13
* New functionality should have test cases. Preferably write the
14
test before writing the code.
16
In general, you can test at either the command-line level or the
17
internal API level. See Writing Tests below for more detail.
19
* Try to practice Test-Driven Development. before fixing a bug, write a
20
test case so that it does not regress. Similarly for adding a new
21
feature: write a test case for a small version of the new feature before
22
starting on the code itself. Check the test fails on the old code, then
23
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.
611
28
* Imports should be done at the top-level of the file, unless there is
612
29
a strong reason to have them lazily loaded when a particular
616
33
* Module names should always be given fully-qualified,
617
34
i.e. ``bzrlib.hashcache`` not just ``hashcache``.
36
* Commands should return non-zero when they encounter circumstances that
37
the user should really pay attention to - which includes trivial shell
40
Recommended values are
42
1- Conflicts in merge-like operations, or changes are present in
44
2- Unrepresentable diff changes (i.e. binary files that we cannot show
46
3- An error or exception has occurred.
51
We have a commitment to 6 months API stability - any supported symbol in a
52
release of bzr MUST NOT be altered in any way that would result in
53
breaking existing code that uses it. That means that method names,
54
parameter ordering, parameter names, variable and attribute names etc must
55
not be changed without leaving a 'deprecated forwarder' behind. This even
56
applies to modules and classes.
58
If you wish to change the behaviour of a supported API in an incompatible
59
way, you need to change its name as well. For instance, if I add a optional keyword
60
parameter to branch.commit - that's fine. On the other hand, if I add a
61
keyword parameter to branch.commit which is a *required* transaction
62
object, I should rename the API - i.e. to 'branch.commit_transaction'.
64
When renaming such supported API's, be sure to leave a deprecated_method (or
65
_function or ...) behind which forwards to the new API. See the
66
bzrlib.symbol_versioning module for decorators that take care of the
67
details for you - such as updating the docstring, and issuing a warning
68
when the old api is used.
70
For unsupported API's, it does not hurt to follow this discipline, but its
71
not required. Minimally though, please try to rename things so that
72
callers will at least get an AttributeError rather than weird results.
75
Standard parameter types
76
------------------------
78
There are some common requirements in the library: some parameters need to be
79
unicode safe, some need byte strings, and so on. At the moment we have
80
only codified one specific pattern: Parameters that need to be unicode
81
should be check via 'bzrlib.osutils.safe_unicode'. This will coerce the
82
input into unicode in a consistent fashion, allowing trivial strings to be
83
used for programmer convenience, but not performing unpredictably in the
84
presence of different locales.
89
If you change the behaviour of a command, please update its docstring
90
in bzrlib/commands.py. This is displayed by the 'bzr help' command.
95
If you make a user-visible change, please add a note to the NEWS file.
96
The description should be written to make sense to someone who's just
97
a user of bzr, not a developer: new functions or classes shouldn't be
98
mentioned, but new commands, changes in behaviour or fixed nontrivial
99
bugs should be listed. See the existing entries for an idea of what
102
Within each release, entries in the news file should have the most
103
user-visible changes first. So the order should be approximately:
105
* changes to existing behaviour - the highest priority because the
106
user's existing knowledge is incorrect
107
* new features - should be brought to their attention
108
* bug fixes - may be of interest if the bug was affecting them, and
109
should include the bug number if any
110
* major documentation changes
111
* changes to internal interfaces
113
People who made significant contributions to each change are listed in
114
parenthesis. This can include reporting bugs (particularly with good
115
details or reproduction recipes), submitting patches, etc.
120
Functions, methods, classes and modules should have docstrings
121
describing how they are used.
123
The first line of the docstring should be a self-contained sentence.
125
For the special case of Command classes, this acts as the user-visible
126
documentation shown by the help command.
128
The docstrings should be formatted as reStructuredText_ (like this
129
document), suitable for processing using the epydoc_ tool into HTML
132
.. _reStructuredText: http://docutils.sourceforge.net/rst.html
133
.. _epydoc: http://epydoc.sourceforge.net/
140
Please write PEP-8__ compliant code.
142
One often-missed requirement is that the first line of docstrings
143
should be a self-contained one-sentence summary.
145
__ http://www.python.org/peps/pep-0008.html
623
Functions, methods or members that are relatively private are given
624
a leading underscore prefix. Names without a leading underscore are
625
public not just across modules but to programmers using bzrlib as an
152
Functions, methods or members that are in some sense "private" are given
153
a leading underscore prefix. This is just a hint that code outside the
154
implementation should probably not use that interface.
628
156
We prefer class names to be concatenated capital words (``TestCase``)
629
157
and variables, methods and functions to be lowercase words joined by
699
209
> factory, then yes, foo_factory is what I would use.
705
Several places in Bazaar use (or will use) a registry, which is a
706
mapping from names to objects or classes. The registry allows for
707
loading in registered code only when it's needed, and keeping
708
associated information such as a help string or description.
711
InterObject and multiple dispatch
712
=================================
714
The ``InterObject`` provides for two-way `multiple dispatch`__: matching
715
up for example a source and destination repository to find the right way
716
to transfer data between them.
718
.. __: http://en.wikipedia.org/wiki/Multiple_dispatch
720
There is a subclass ``InterObject`` classes for each type of object that is
721
dispatched this way, e.g. ``InterRepository``. Calling ``.get()`` on this
722
class will return an ``InterObject`` instance providing the best match for
723
those parameters, and this instance then has methods for operations
726
inter = InterRepository.get(source_repo, target_repo)
727
inter.fetch(revision_id)
729
``InterRepository`` also acts as a registry-like object for its
730
subclasses, and they can be added through ``.register_optimizer``. The
731
right one to run is selected by asking each class, in reverse order of
732
registration, whether it ``.is_compatible`` with the relevant objects.
737
To make startup time faster, we use the ``bzrlib.lazy_import`` module to
738
delay importing modules until they are actually used. ``lazy_import`` uses
739
the same syntax as regular python imports. So to import a few modules in a
742
from bzrlib.lazy_import import lazy_import
743
lazy_import(globals(), """
752
revision as _mod_revision,
754
import bzrlib.transport
758
At this point, all of these exist as a ``ImportReplacer`` object, ready to
759
be imported once a member is accessed. Also, when importing a module into
760
the local namespace, which is likely to clash with variable names, it is
761
recommended to prefix it as ``_mod_<module>``. This makes it clearer that
762
the variable is a module, and these object should be hidden anyway, since
763
they shouldn't be imported into other namespaces.
765
While it is possible for ``lazy_import()`` to import members of a module
766
when using the ``from module import member`` syntax, it is recommended to
767
only use that syntax to load sub modules ``from module import submodule``.
768
This is because variables and classes can frequently be used without
769
needing a sub-member for example::
771
lazy_import(globals(), """
772
from module import MyClass
776
return isinstance(x, MyClass)
778
This will incorrectly fail, because ``MyClass`` is a ``ImportReplacer``
779
object, rather than the real class.
781
It also is incorrect to assign ``ImportReplacer`` objects to other variables.
782
Because the replacer only knows about the original name, it is unable to
783
replace other variables. The ``ImportReplacer`` class will raise an
784
``IllegalUseOfScopeReplacer`` exception if it can figure out that this
785
happened. But it requires accessing a member more than once from the new
786
variable, so some bugs are not detected right away.
792
The null revision is the ancestor of all revisions. Its revno is 0, its
793
revision-id is ``null:``, and its tree is the empty tree. When referring
794
to the null revision, please use ``bzrlib.revision.NULL_REVISION``. Old
795
code sometimes uses ``None`` for the null revision, but this practice is
799
Object string representations
800
=============================
802
Python prints objects using their ``__repr__`` method when they are
803
written to logs, exception tracebacks, or the debugger. We want
804
objects to have useful representations to help in determining what went
807
If you add a new class you should generally add a ``__repr__`` method
808
unless there is an adequate method in a parent class. There should be a
811
Representations should typically look like Python constructor syntax, but
812
they don't need to include every value in the object and they don't need
813
to be able to actually execute. They're to be read by humans, not
814
machines. Don't hardcode the classname in the format, so that we get the
815
correct value if the method is inherited by a subclass. If you're
816
printing attributes of the object, including strings, you should normally
817
use ``%r`` syntax (to call their repr in turn).
819
Try to avoid the representation becoming more than one or two lines long.
820
(But balance this against including useful information, and simplicity of
823
Because repr methods are often called when something has already gone
824
wrong, they should be written somewhat more defensively than most code.
825
The object may be half-initialized or in some other way in an illegal
826
state. The repr method shouldn't raise an exception, or it may hide the
827
(probably more useful) underlying exception.
832
return '%s(%r)' % (self.__class__.__name__,
839
A bare ``except`` statement will catch all exceptions, including ones that
840
really should terminate the program such as ``MemoryError`` and
841
``KeyboardInterrupt``. They should rarely be used unless the exception is
842
later re-raised. Even then, think about whether catching just
843
``Exception`` (which excludes system errors in Python2.5 and later) would
850
All code should be exercised by the test suite. See the `Bazaar Testing
851
Guide <http://doc.bazaar-vcs.org/developers/testing.html>`_ for detailed
852
information about writing tests.
861
We don't change APIs in stable branches: any supported symbol in a stable
862
release of bzr must not be altered in any way that would result in
863
breaking existing code that uses it. That means that method names,
864
parameter ordering, parameter names, variable and attribute names etc must
865
not be changed without leaving a 'deprecated forwarder' behind. This even
866
applies to modules and classes.
868
If you wish to change the behaviour of a supported API in an incompatible
869
way, you need to change its name as well. For instance, if I add an optional keyword
870
parameter to branch.commit - that's fine. On the other hand, if I add a
871
keyword parameter to branch.commit which is a *required* transaction
872
object, I should rename the API - i.e. to 'branch.commit_transaction'.
874
(Actually, that may break code that provides a new implementation of
875
``commit`` and doesn't expect to receive the parameter.)
877
When renaming such supported API's, be sure to leave a deprecated_method (or
878
_function or ...) behind which forwards to the new API. See the
879
bzrlib.symbol_versioning module for decorators that take care of the
880
details for you - such as updating the docstring, and issuing a warning
881
when the old API is used.
883
For unsupported API's, it does not hurt to follow this discipline, but it's
884
not required. Minimally though, please try to rename things so that
885
callers will at least get an AttributeError rather than weird results.
888
Deprecation decorators
889
----------------------
891
``bzrlib.symbol_versioning`` provides decorators that can be attached to
892
methods, functions, and other interfaces to indicate that they should no
893
longer be used. For example::
895
@deprecated_method(deprecated_in((0, 1, 4)))
897
return self._new_foo()
899
To deprecate a static method you must call ``deprecated_function``
900
(**not** method), after the staticmethod call::
903
@deprecated_function(deprecated_in((0, 1, 4)))
904
def create_repository(base, shared=False, format=None):
906
When you deprecate an API, you should not just delete its tests, because
907
then we might introduce bugs in them. If the API is still present at all,
908
it should still work. The basic approach is to use
909
``TestCase.applyDeprecated`` which in one step checks that the API gives
910
the expected deprecation message, and also returns the real result from
911
the method, so that tests can keep running.
913
Deprecation warnings will be suppressed for final releases, but not for
914
development versions or release candidates, or when running ``bzr
915
selftest``. This gives developers information about whether their code is
916
using deprecated functions, but avoids confusing users about things they
923
Processing Command Lines
924
------------------------
926
bzrlib has a standard framework for parsing command lines and calling
927
processing routines associated with various commands. See builtins.py
928
for numerous examples.
931
Standard Parameter Types
932
------------------------
934
There are some common requirements in the library: some parameters need to be
935
unicode safe, some need byte strings, and so on. At the moment we have
936
only codified one specific pattern: Parameters that need to be unicode
937
should be checked via ``bzrlib.osutils.safe_unicode``. This will coerce the
938
input into unicode in a consistent fashion, allowing trivial strings to be
939
used for programmer convenience, but not performing unpredictably in the
940
presence of different locales.
946
215
(The strategy described here is what we want to get to, but it's not
977
246
should be only in the command-line tool.
980
Progress and Activity Indications
981
---------------------------------
983
bzrlib has a way for code to display to the user that stuff is happening
984
during a long operation. There are two particular types: *activity* which
985
means that IO is happening on a Transport, and *progress* which means that
986
higher-level application work is occurring. Both are drawn together by
989
Transport objects are responsible for calling `report_transport_activity`
992
Progress uses a model/view pattern: application code acts on a
993
`ProgressTask` object, which notifies the UI when it needs to be
994
displayed. Progress tasks form a stack. To create a new progress task on
995
top of the stack, call `bzrlib.ui.ui_factory.nested_progress_bar()`, then
996
call `update()` on the returned ProgressTask. It can be updated with just
997
a text description, with a numeric count, or with a numeric count and
998
expected total count. If an expected total count is provided the view
999
can show the progress moving along towards the expected total.
1001
The user should call `finish` on the `ProgressTask` when the logical
1002
operation has finished, so it can be removed from the stack.
1004
Progress tasks have a complex relationship with generators: it's a very
1005
good place to use them, but because python2.4 does not allow ``finally``
1006
blocks in generators it's hard to clean them up properly. In this case
1007
it's probably better to have the code calling the generator allocate a
1008
progress task for its use and then call `finalize` when it's done, which
1009
will close it if it was not already closed. The generator should also
1010
finish the progress task when it exits, because it may otherwise be a long
1011
time until the finally block runs.
1017
Bazaar has online help for various topics through ``bzr help COMMAND`` or
1018
equivalently ``bzr command -h``. We also have help on command options,
1019
and on other help topics. (See ``help_topics.py``.)
1021
As for python docstrings, the first paragraph should be a single-sentence
1022
synopsis of the command.
1024
The help for options should be one or more proper sentences, starting with
1025
a capital letter and finishing with a full stop (period).
1027
All help messages and documentation should have two spaces between
1031
Handling Errors and Exceptions
1032
==============================
1034
Commands should return non-zero when they encounter circumstances that
1035
the user should really pay attention to - which includes trivial shell
1038
Recommended values are:
1041
1. Conflicts in merge-like operations, or changes are present in
1042
diff-like operations.
1043
2. Unrepresentable diff changes (i.e. binary files that we cannot show
1045
3. An error or exception has occurred.
1046
4. An internal error occurred (one that shows a traceback.)
1048
Errors are handled through Python exceptions. Exceptions should be defined
1049
inside bzrlib.errors, so that we can see the whole tree at a glance.
1051
We broadly classify errors as either being either internal or not,
1052
depending on whether ``internal_error`` is set or not. If we think it's our
1053
fault, we show a backtrace, an invitation to report the bug, and possibly
1054
other details. This is the default for errors that aren't specifically
1055
recognized as being caused by a user error. Otherwise we show a briefer
1056
message, unless -Derror was given.
1058
Many errors originate as "environmental errors" which are raised by Python
1059
or builtin libraries -- for example IOError. These are treated as being
1060
our fault, unless they're caught in a particular tight scope where we know
1061
that they indicate a user errors. For example if the repository format
1062
is not found, the user probably gave the wrong path or URL. But if one of
1063
the files inside the repository is not found, then it's our fault --
1064
either there's a bug in bzr, or something complicated has gone wrong in
1065
the environment that means one internal file was deleted.
1067
Many errors are defined in ``bzrlib/errors.py`` but it's OK for new errors
1068
to be added near the place where they are used.
1070
Exceptions are formatted for the user by conversion to a string
1071
(eventually calling their ``__str__`` method.) As a convenience the
1072
``._fmt`` member can be used as a template which will be mapped to the
1073
error's instance dict.
1075
New exception classes should be defined when callers might want to catch
1076
that exception specifically, or when it needs a substantially different
1079
#. If it is something that a caller can recover from, a custom exception
1082
#. If it is a data consistency issue, using a builtin like
1083
``ValueError``/``TypeError`` is reasonable.
1085
#. If it is a programmer error (using an api incorrectly)
1086
``AssertionError`` is reasonable.
1088
#. Otherwise, use ``BzrError`` or ``InternalBzrError``.
1090
Exception strings should start with a capital letter and should not have a
1091
final fullstop. If long, they may contain newlines to break the text.
1097
Do not use the Python ``assert`` statement, either in tests or elsewhere.
1098
A source test checks that it is not used. It is ok to explicitly raise
1103
* It makes the behaviour vary depending on whether bzr is run with -O
1104
or not, therefore giving a chance for bugs that occur in one case or
1105
the other, several of which have already occurred: assertions with
1106
side effects, code which can't continue unless the assertion passes,
1107
cases where we should give the user a proper message rather than an
1109
* It's not that much shorter than an explicit if/raise.
1110
* It tends to lead to fuzzy thinking about whether the check is
1111
actually needed or not, and whether it's an internal error or not
1112
* It tends to cause look-before-you-leap patterns.
1113
* It's unsafe if the check is needed to protect the integrity of the
1115
* It tends to give poor messages since the developer can get by with
1116
no explanatory text at all.
1117
* We can't rely on people always running with -O in normal use, so we
1118
can't use it for tests that are actually expensive.
1119
* Expensive checks that help developers are better turned on from the
1120
test suite or a -D flag.
1121
* If used instead of ``self.assert*()`` in tests it makes them falsely pass with -O.
1127
When you change bzrlib, please update the relevant documentation for the
1128
change you made: Changes to commands should update their help, and
1129
possibly end user tutorials; changes to the core library should be
1130
reflected in API documentation.
1135
If you make a user-visible change, please add a note to the NEWS file.
1136
The description should be written to make sense to someone who's just
1137
a user of bzr, not a developer: new functions or classes shouldn't be
1138
mentioned, but new commands, changes in behaviour or fixed nontrivial
1139
bugs should be listed. See the existing entries for an idea of what
1142
Within each release, entries in the news file should have the most
1143
user-visible changes first. So the order should be approximately:
1145
* changes to existing behaviour - the highest priority because the
1146
user's existing knowledge is incorrect
1147
* new features - should be brought to their attention
1148
* bug fixes - may be of interest if the bug was affecting them, and
1149
should include the bug number if any
1150
* major documentation changes, including fixed documentation bugs
1151
* changes to internal interfaces
1153
People who made significant contributions to each change are listed in
1154
parenthesis. This can include reporting bugs (particularly with good
1155
details or reproduction recipes), submitting patches, etc.
1157
To help with merging, NEWS entries should be sorted lexicographically
1158
within each section.
251
In general tests should be placed in a file named test_FOO.py where
252
FOO is the logical thing under test. That file should be placed in the
253
tests subdirectory under the package being tested.
255
For example, tests for merge3 in bzrlib belong in bzrlib/tests/test_merge3.py.
256
See bzrlib/selftest/test_sampler.py for a template test script.
258
Tests can be written for the UI or for individual areas of the library.
259
Choose whichever is appropriate: if adding a new command, or a new command
260
option, then you should be writing a UI test. If you are both adding UI
261
functionality and library functionality, you will want to write tests for
262
both the UI and the core behaviours. We call UI tests 'blackbox' tests
263
and they are found in bzrlib/tests/blackbox/*.py.
265
When writing blackbox tests please honour the following conventions:
267
1. Place the tests for the command 'name' in
268
bzrlib/tests/blackbox/test_name.py. This makes it easy for developers
269
to locate the test script for a faulty command.
271
2. Use the 'self.run_bzr("name")' utility function to invoke the command
272
rather than running bzr in a subprocess or invoking the
273
cmd_object.run() method directly. This is a lot faster than
274
subprocesses and generates the same logging output as running it in a
275
subprocess (which invoking the method directly does not).
277
3. Only test the one command in a single test script. Use the bzrlib
278
library when setting up tests and when evaluating the side-effects of
279
the command. We do this so that the library api has continual pressure
280
on it to be as functional as the command line in a simple manner, and
281
to isolate knock-on effects throughout the blackbox test suite when a
282
command changes it name or signature. Ideally only the tests for a
283
given command are affected when a given command is changed.
1163
The docstring of a command is used by ``bzr help`` to generate help output
1164
for the command. The list 'takes_options' attribute on a command is used by
1165
``bzr help`` to document the options for the command - the command
1166
docstring does not need to document them. Finally, the '_see_also'
1167
attribute on a command can be used to reference other related help topics.
1172
Functions, methods, classes and modules should have docstrings
1173
describing how they are used.
1175
The first line of the docstring should be a self-contained sentence.
1177
For the special case of Command classes, this acts as the user-visible
1178
documentation shown by the help command.
1180
The docstrings should be formatted as reStructuredText_ (like this
1181
document), suitable for processing using the epydoc_ tool into HTML
1184
.. _reStructuredText: http://docutils.sourceforge.net/rst.html
1185
.. _epydoc: http://epydoc.sourceforge.net/
1194
The copyright policy for bzr was recently made clear in this email (edited
1195
for grammatical correctness)::
1197
The attached patch cleans up the copyright and license statements in
1198
the bzr source. It also adds tests to help us remember to add them
1199
with the correct text.
1201
We had the problem that lots of our files were "Copyright Canonical
1202
Development Ltd" which is not a real company, and some other variations
1203
on this theme. Also, some files were missing the GPL statements.
1205
I want to be clear about the intent of this patch, since copyright can
1206
be a little controversial.
1208
1) The big motivation for this is not to shut out the community, but
1209
just to clean up all of the invalid copyright statements.
1211
2) It has been the general policy for bzr that we want a single
1212
copyright holder for all of the core code. This is following the model
1213
set by the FSF, which makes it easier to update the code to a new
1214
license in case problems are encountered. (For example, if we want to
1215
upgrade the project universally to GPL v3 it is much simpler if there is
1216
a single copyright holder). It also makes it clearer if copyright is
1217
ever debated, there is a single holder, which makes it easier to defend
1218
in court, etc. (I think the FSF position is that if you assign them
1219
copyright, they can defend it in court rather than you needing to, and
1220
I'm sure Canonical would do the same).
1221
As such, Canonical has requested copyright assignments from all of the
1224
3) If someone wants to add code and not attribute it to Canonical, there
1225
is a specific list of files that are excluded from this check. And the
1226
test failure indicates where that is, and how to update it.
1228
4) If anyone feels that I changed a copyright statement incorrectly, just
1229
let me know, and I'll be happy to correct it. Whenever you have large
1230
mechanical changes like this, it is possible to make some mistakes.
1232
Just to reiterate, this is a community project, and it is meant to stay
1233
that way. Core bzr code is copyright Canonical for legal reasons, and
1234
the tests are just there to help us maintain that.
1237
Miscellaneous Topics
1238
####################
1243
Bazaar has a few facilities to help debug problems by going into pdb_, the
1246
.. _pdb: http://docs.python.org/lib/debugger-commands.html
1248
If the ``BZR_PDB`` environment variable is set
1249
then bzr will go into pdb post-mortem mode when an unhandled exception
1252
If you send a SIGQUIT or SIGBREAK signal to bzr then it will drop into the
1253
debugger immediately. SIGQUIT can be generated by pressing Ctrl-\\ on
1254
Unix. SIGBREAK is generated with Ctrl-Pause on Windows (some laptops have
1255
this as Fn-Pause). You can continue execution by typing ``c``. This can
1256
be disabled if necessary by setting the environment variable
1257
``BZR_SIGQUIT_PDB=0``.
1263
Bazaar accepts some global options starting with ``-D`` such as
1264
``-Dhpss``. These set a value in `bzrlib.debug.debug_flags`, and
1265
typically cause more information to be written to the trace file. Most
1266
`mutter` calls should be guarded by a check of those flags so that we
1267
don't write out too much information if it's not needed.
1269
Debug flags may have effects other than just emitting trace messages.
1271
Run ``bzr help global-options`` to see them all.
1273
These flags may also be set as a comma-separated list in the
1274
``debug_flags`` option in e.g. ``~/.bazaar/bazaar.conf``. (Note that it
1275
must be in this global file, not in the branch or location configuration,
1276
because it's currently only loaded at startup time.) For instance you may
1277
want to always record hpss traces and to see full error tracebacks::
1279
debug_flags = hpss, error
288
We make selective use of doctests__. In general they should provide
289
*examples* within the API documentation which can incidentally be tested. We
290
don't try to test every important case using doctests -- regular Python
291
tests are generally a better solution.
293
Most of these are in ``bzrlib/doc/api``. More additions are welcome.
295
__ http://docs.python.org/lib/module-doctest.html
300
Currently, bzr selftest is used to invoke tests.
301
You can provide a pattern argument to run a subset. For example,
302
to run just the blackbox tests, run::
304
./bzr selftest -v blackbox
306
To skip a particular test (or set of tests), you need to use a negative
308
./bzr selftest '^(?!.*blackbox)'
311
Errors and exceptions
312
=====================
314
Errors are handled through Python exceptions. They can represent user
315
errors, environmental errors or program bugs. Sometimes we can't be sure
316
at the time it's raised which case applies. See bzrlib/errors.py for
317
details on the error-handling practices.
1288
326
indexes into the branch's revision history.
1291
Unicode and Encoding Support
1292
============================
1294
This section discusses various techniques that Bazaar uses to handle
1295
characters that are outside the ASCII set.
1300
When a ``Command`` object is created, it is given a member variable
1301
accessible by ``self.outf``. This is a file-like object, which is bound to
1302
``sys.stdout``, and should be used to write information to the screen,
1303
rather than directly writing to ``sys.stdout`` or calling ``print``.
1304
This file has the ability to translate Unicode objects into the correct
1305
representation, based on the console encoding. Also, the class attribute
1306
``encoding_type`` will effect how unprintable characters will be
1307
handled. This parameter can take one of 3 values:
1310
Unprintable characters will be represented with a suitable replacement
1311
marker (typically '?'), and no exception will be raised. This is for
1312
any command which generates text for the user to review, rather than
1313
for automated processing.
1314
For example: ``bzr log`` should not fail if one of the entries has text
1315
that cannot be displayed.
1318
Attempting to print an unprintable character will cause a UnicodeError.
1319
This is for commands that are intended more as scripting support, rather
1320
than plain user review.
1321
For example: ``bzr ls`` is designed to be used with shell scripting. One
1322
use would be ``bzr ls --null --unknowns | xargs -0 rm``. If ``bzr``
1323
printed a filename with a '?', the wrong file could be deleted. (At the
1324
very least, the correct file would not be deleted). An error is used to
1325
indicate that the requested action could not be performed.
1328
Do not attempt to automatically convert Unicode strings. This is used
1329
for commands that must handle conversion themselves.
1330
For example: ``bzr diff`` needs to translate Unicode paths, but should
1331
not change the exact text of the contents of the files.
1334
``bzrlib.urlutils.unescape_for_display``
1335
----------------------------------------
1337
Because Transports work in URLs (as defined earlier), printing the raw URL
1338
to the user is usually less than optimal. Characters outside the standard
1339
set are printed as escapes, rather than the real character, and local
1340
paths would be printed as ``file://`` urls. The function
1341
``unescape_for_display`` attempts to unescape a URL, such that anything
1342
that cannot be printed in the current encoding stays an escaped URL, but
1343
valid characters are generated where possible.
1349
The ``bzrlib.osutils`` module has many useful helper functions, including
1350
some more portable variants of functions in the standard library.
1352
In particular, don't use ``shutil.rmtree`` unless it's acceptable for it
1353
to fail on Windows if some files are readonly or still open elsewhere.
1354
Use ``bzrlib.osutils.rmtree`` instead.
1360
We write some extensions in C using pyrex. We design these to work in
1363
* User with no C compiler
1364
* User with C compiler
1367
The recommended way to install bzr is to have a C compiler so that the
1368
extensions can be built, but if no C compiler is present, the pure python
1369
versions we supply will work, though more slowly.
1371
For developers we recommend that pyrex be installed, so that the C
1372
extensions can be changed if needed.
1374
For the C extensions, the extension module should always match the
1375
original python one in all respects (modulo speed). This should be
1376
maintained over time.
1378
To create an extension, add rules to setup.py for building it with pyrex,
1379
and with distutils. Now start with an empty .pyx file. At the top add
1380
"include 'yourmodule.py'". This will import the contents of foo.py into this
1381
file at build time - remember that only one module will be loaded at
1382
runtime. Now you can subclass classes, or replace functions, and only your
1383
changes need to be present in the .pyx file.
1385
Note that pyrex does not support all 2.4 programming idioms, so some
1386
syntax changes may be required. I.e.
1388
- 'from foo import (bar, gam)' needs to change to not use the brackets.
1389
- 'import foo.bar as bar' needs to be 'import foo.bar; bar = foo.bar'
1391
If the changes are too dramatic, consider
1392
maintaining the python code twice - once in the .pyx, and once in the .py,
1393
and no longer including the .py file.
1396
Making Installers for OS Windows
1397
================================
1398
To build a win32 installer, see the instructions on the wiki page:
1399
http://bazaar-vcs.org/BzrWin32Installer
1402
Core Developer Tasks
1403
####################
1408
What is a Core Developer?
1409
-------------------------
1411
While everyone in the Bazaar community is welcome and encouraged to
1412
propose and submit changes, a smaller team is reponsible for pulling those
1413
changes together into a cohesive whole. In addition to the general developer
1414
stuff covered above, "core" developers have responsibility for:
1417
* reviewing blueprints
1419
* managing releases (see `Releasing Bazaar <http://doc.bazaar-vcs.org/developers/releasing.html>`_)
1422
Removing barriers to community participation is a key reason for adopting
1423
distributed VCS technology. While DVCS removes many technical barriers,
1424
a small number of social barriers are often necessary instead.
1425
By documenting how the above things are done, we hope to
1426
encourage more people to participate in these activities, keeping the
1427
differences between core and non-core contributors to a minimum.
1430
Communicating and Coordinating
1431
------------------------------
1433
While it has many advantages, one of the challenges of distributed
1434
development is keeping everyone else aware of what you're working on.
1435
There are numerous ways to do this:
1437
#. Assign bugs to yourself in Launchpad
1438
#. Mention it on the mailing list
1439
#. Mention it on IRC
1441
As well as the email notifcations that occur when merge requests are sent
1442
and reviewed, you can keep others informed of where you're spending your
1443
energy by emailing the **bazaar-commits** list implicitly. To do this,
1444
install and configure the Email plugin. One way to do this is add these
1445
configuration settings to your central configuration file (e.g.
1446
``~/.bazaar/bazaar.conf`` on Linux)::
1449
email = Joe Smith <joe.smith@internode.on.net>
1450
smtp_server = mail.internode.on.net:25
1452
Then add these lines for the relevant branches in ``locations.conf``::
1454
post_commit_to = bazaar-commits@lists.canonical.com
1455
post_commit_mailer = smtplib
1457
While attending a sprint, RobertCollins' Dbus plugin is useful for the
1458
same reason. See the documentation within the plugin for information on
1459
how to set it up and configure it.
1468
Of the many workflows supported by Bazaar, the one adopted for Bazaar
1469
development itself is known as "Decentralized with automatic gatekeeper".
1470
To repeat the explanation of this given on
1471
http://bazaar-vcs.org/Workflows:
1474
In this workflow, each developer has their own branch or
1475
branches, plus read-only access to the mainline. A software gatekeeper
1476
(e.g. PQM) has commit rights to the main branch. When a developer wants
1477
their work merged, they request the gatekeeper to merge it. The gatekeeper
1478
does a merge, a compile, and runs the test suite. If the code passes, it
1479
is merged into the mainline.
1481
In a nutshell, here's the overall submission process:
1483
#. get your work ready (including review except for trivial changes)
1484
#. push to a public location
1485
#. ask PQM to merge from that location
1488
At present, PQM always takes the changes to merge from a branch
1489
at a URL that can be read by it. For Bazaar, that means a public,
1490
typically http, URL.
1492
As a result, the following things are needed to use PQM for submissions:
1494
#. A publicly available web server
1495
#. Your OpenPGP key registered with PQM (contact RobertCollins for this)
1496
#. The PQM plugin installed and configured (not strictly required but
1497
highly recommended).
1500
Selecting a Public Branch Location
1501
----------------------------------
1503
If you don't have your own web server running, branches can always be
1504
pushed to Launchpad. Here's the process for doing that:
1506
Depending on your location throughout the world and the size of your
1507
repository though, it is often quicker to use an alternative public
1508
location to Launchpad, particularly if you can set up your own repo and
1509
push into that. By using an existing repo, push only needs to send the
1510
changes, instead of the complete repository every time. Note that it is
1511
easy to register branches in other locations with Launchpad so no benefits
1512
are lost by going this way.
1515
For Canonical staff, http://people.ubuntu.com/~<user>/ is one
1516
suggestion for public http branches. Contact your manager for information
1517
on accessing this system if required.
1519
It should also be noted that best practice in this area is subject to
1520
change as things evolve. For example, once the Bazaar smart server on
1521
Launchpad supports server-side branching, the performance situation will
1522
be very different to what it is now (Jun 2007).
1525
Configuring the PQM Plug-In
1526
---------------------------
1528
While not strictly required, the PQM plugin automates a few things and
1529
reduces the chance of error. Before looking at the plugin, it helps to
1530
understand a little more how PQM operates. Basically, PQM requires an
1531
email indicating what you want it to do. The email typically looks like
1534
star-merge source-branch target-branch
1538
star-merge http://bzr.arbash-meinel.com/branches/bzr/jam-integration http://bazaar-vcs.org/bzr/bzr.dev
1540
Note that the command needs to be on one line. The subject of the email
1541
will be used for the commit message. The email also needs to be ``gpg``
1542
signed with a key that PQM accepts.
1544
The advantages of using the PQM plugin are:
1546
#. You can use the config policies to make it easy to set up public
1547
branches, so you don't have to ever type the full paths you want to merge
1550
#. It checks to make sure the public branch last revision matches the
1551
local last revision so you are submitting what you think you are.
1553
#. It uses the same public_branch and smtp sending settings as bzr-email,
1554
so if you have one set up, you have the other mostly set up.
1556
#. Thunderbird refuses to not wrap lines, and request lines are usually
1557
pretty long (you have 2 long URLs in there).
1559
Here are sample configuration settings for the PQM plugin. Here are the
1560
lines in bazaar.conf::
1563
email = Joe Smith <joe.smith@internode.on.net>
1564
smtp_server=mail.internode.on.net:25
1566
And here are the lines in ``locations.conf`` (or ``branch.conf`` for
1567
dirstate-tags branches)::
1569
[/home/joe/bzr/my-integration]
1570
push_location = sftp://joe-smith@bazaar.launchpad.net/%7Ejoe-smith/bzr/my-integration/
1571
push_location:policy = norecurse
1572
public_branch = http://bazaar.launchpad.net/~joe-smith/bzr/my-integration/
1573
public_branch:policy = appendpath
1574
pqm_email = Bazaar PQM <pqm@bazaar-vcs.org>
1575
pqm_branch = http://bazaar-vcs.org/bzr/bzr.dev
1577
Note that the push settings will be added by the first ``push`` on
1578
a branch. Indeed the preferred way to generate the lines above is to use
1579
``push`` with an argument, then copy-and-paste the other lines into
1586
Here is one possible recipe once the above environment is set up:
1588
#. pull bzr.dev => my-integration
1589
#. merge patch => my-integration
1590
#. fix up any final merge conflicts (NEWS being the big killer here).
1596
The ``push`` step is not required if ``my-integration`` is a checkout of
1599
Because of defaults, you can type a single message into commit and
1600
pqm-commit will reuse that.
1603
Tracking Change Acceptance
1604
--------------------------
1606
The web interface to PQM is https://pqm.bazaar-vcs.org/. After submitting
1607
a change, you can visit this URL to confirm it was received and placed in
1610
When PQM completes processing a change, an email is sent to you with the
1614
Reviewing Blueprints
332
The ``Transport`` layer handles access to local or remote directories.
333
Each Transport object acts like a logical connection to a particular
334
directory, and it allows various operations on files within it. You can
335
*clone* a transport to get a new Transport connected to a subdirectory or
338
Transports are not used for access to the working tree. At present
339
working trees are always local and they are accessed through the regular
340
Python file io mechanisms.
345
Transports work in URLs. Take note that URLs are by definition only
346
ASCII - the decision of how to encode a Unicode string into a URL must be
347
taken at a higher level, typically in the Store. (Note that Stores also
348
escape filenames which cannot be safely stored on all filesystems, but
349
this is a different level.)
351
The main reason for this is that it's not possible to safely roundtrip a
352
URL into Unicode and then back into the same URL. The URL standard
353
gives a way to represent non-ASCII bytes in ASCII (as %-escapes), but
354
doesn't say how those bytes represent non-ASCII characters. (They're not
355
guaranteed to be UTF-8 -- that is common but doesn't happen everywhere.)
357
For example if the user enters the url ``http://example/%e0`` there's no
358
way to tell whether that character represents "latin small letter a with
359
grave" in iso-8859-1, or "latin small letter r with acute" in iso-8859-2
360
or malformed UTF-8. So we can't convert their URL to Unicode reliably.
362
Equally problematic if we're given a url-like string containing non-ascii
363
characters (such as the accented a) we can't be sure how to convert that
364
to the correct URL, because we don't know what encoding the server expects
365
for those characters. (Although this is not totally reliable we might still
366
accept these and assume they should be put into UTF-8.)
368
A similar edge case is that the url ``http://foo/sweet%2Fsour" contains
369
one directory component whose name is "sweet/sour". The escaped slash is
370
not a directory separator. If we try to convert URLs to regular Unicode
371
paths this information will be lost.
373
This implies that Transports must natively deal with URLs; for simplicity
374
they *only* deal with URLs and conversion of other strings to URLs is done
375
elsewhere. Information they return, such as from ``list_dir``, is also in
376
the form of URL components.
1615
380
====================
1617
Blueprint Tracking Using Launchpad
1618
----------------------------------
1620
New features typically require a fair amount of discussion, design and
1621
debate. For Bazaar, that information is often captured in a so-called
1622
"blueprint" on our Wiki. Overall tracking of blueprints and their status
1623
is done using Launchpad's relevant tracker,
1624
https://blueprints.launchpad.net/bzr/. Once a blueprint for ready for
1625
review, please announce it on the mailing list.
1627
Alternatively, send an email beginning with [RFC] with the proposal to the
1628
list. In some cases, you may wish to attach proposed code or a proposed
1629
developer document if that best communicates the idea. Debate can then
1630
proceed using the normal merge review processes.
1633
Recording Blueprint Review Feedback
1634
-----------------------------------
1636
Unlike its Bug Tracker, Launchpad's Blueprint Tracker doesn't currently
1637
(Jun 2007) support a chronological list of comment responses. Review
1638
feedback can either be recorded on the Wiki hosting the blueprints or by
1639
using Launchpad's whiteboard feature.
1646
Using Releases and Milestones in Launchpad
1647
------------------------------------------
1649
TODO ... (Exact policies still under discussion)
1655
Keeping on top of bugs reported is an important part of ongoing release
1656
planning. Everyone in the community is welcome and encouraged to raise
1657
bugs, confirm bugs raised by others, and nominate a priority. Practically
1658
though, a good percentage of bug triage is often done by the core
1659
developers, partially because of their depth of product knowledge.
1661
With respect to bug triage, core developers are encouraged to play an
1662
active role with particular attention to the following tasks:
1664
* keeping the number of unconfirmed bugs low
1665
* ensuring the priorities are generally right (everything as critical - or
1666
medium - is meaningless)
1667
* looking out for regressions and turning those around sooner rather than later.
1670
As well as prioritizing bugs and nominating them against a
1671
target milestone, Launchpad lets core developers offer to mentor others in
1676
vim: ft=rst tw=74 ai
382
If you'd like to propose a change, please post to the
383
bazaar-ng@lists.canonical.com list with a patch, bzr changeset, or link to a
384
branch. Please put '[patch]' in the subject so we can pick them out, and
385
include some text explaining the change. Remember to put an update to the NEWS
386
file in your diff, if it makes any changes visible to users or plugin
387
developers. Please include a diff against mainline if you're giving a link to
390
Please indicate if you think the code is ready to merge, or if it's just a
391
draft or for discussion. If you want comments from many developers rather than
392
to be merged, you can put '[rfc]' in the subject lines.
394
Anyone is welcome to review code. There are broadly three gates for
397
* Doesn't reduce test coverage: if it adds new methods or commands,
398
there should be tests for them. There is a good test framework
399
and plenty of examples to crib from, but if you are having trouble
400
working out how to test something feel free to post a draft patch
403
* Doesn't reduce design clarity, such as by entangling objects
404
we're trying to separate. This is mostly something the more
405
experienced reviewers need to help check.
407
* Improves bugs, features, speed, or code simplicity.
409
Code that goes in should pass all three.
411
If you read a patch please reply and say so. We can use a numeric scale
412
of -1, -0, +0, +1, meaning respectively "really don't want it in current
413
form", "somewhat uncomfortable", "ok with me", and "please put it in".
414
Anyone can "vote". (It's not really voting, just a terse expression.)
416
If something gets say two +1 votes from core reviewers, and no
417
vetos, then it's OK to come in. Any of the core developers can bring it
418
into their integration branch, which I'll merge regularly. (If you do
419
so, please reply and say so.)
422
:: vim: ft=rst tw=74 ai
added
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HACKING
