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Integrating with Bazaar

This page should hopefully become a quick guide to integrating other (Python-based) software with Bazaar.

Manipulating a Working Tree

Most objects in Bazaar are found in modules that are named after the class they contain. To manipulate the Working Tree you need to create a WorkingTree object, which is located in the workingtree module, e.g.:

from bzrlib.workingtree import WorkingTree

wt = WorkingTree.open('/home/jebw/bzrtest')

This gives us a WorkingTree object, which has methods provided by itself and by its parent classes:: MutableTree and Tree. It's worth looking through these three files (workingtree.py, mutabletree.py and tree.py) to see which methods are available.

Creating a new Working Tree from a branch

If you don't have a working tree at all, you can easily start out here:

from bzrlib.branch import Branch

my_branch = Branch.open(branch_url)
my_branch.create_checkout(TREEDIR, lightweight=True)
my_tree = WorkingTree.open(TREEDIR)

Merging changes

Once you have a branch, you can start pulling in other people's work easily:

other_branch = Branch.open(other_url)
my_tree.merge_from_branch(other_branch)
changes = my_tree.changes_from(my_tree.basis_tree())
print "%s files modified, %s added, %s removed" % (
  len(changes.modified), len(changes.added), len(changes.removed))

Checking conflicts

Of course, it's the case that sometimes merges conflict:

conflicts = my_tree.conflicts()
if not conflicts.is_empty():
    print "EEE conflicts found:"
    for conflict in conflicts:
        print "C " + conflict.path

Comparing trees

There are two methods for comparing trees: changes_from and iter_changes. iter_changes is more regular and precise, but it is somewhat harder to use. See the API documentation for more details.

changes_from creates a Delta object showing changes:

changes = wt.changes_from(wt.basis_tree())

This gives us a Delta object, which has several lists of files for each type of change, e.g. changes.added is a list of added files, changes.removed is list of removed files, changes.modified is a list of modified files. The contents of the lists aren't just filenames, but include other information as well. To grab just the filename, you get the first value, e.g.:

print("list of newly added files")
for filename in changes.added:
  print("%s has been added" % filename[0])

The exception to this is changes.renamed, where the list returned for each renamed file contains both the old and new names -- one or both may interest you, depending on what you're doing.

For example:

print("list of renamed files")
for filename in changes.renamed:
  print("%s has been renamed to %s" % (filename[0], filename[1]))

Adding Files

If you want to add files the same way bzr add does, you can use MutableTree.smart_add. By default, this is recursive. Paths can either be absolute or relative to the workingtree:

wt.smart_add(['dir1/filea.txt', 'fileb.txt',
              '/home/jebw/bzrtesttree/filec.txt'])

For more precise control over which files to add, use MutableTree.add:

wt.add(['dir1/filea.txt', 'fileb.txt', '/home/jebw/bzrtesttree/filec.txt'])

Removing Files

You can remove multiple files together. The file paths need to be relative to the workingtree:

wt.remove(['filea.txt', 'fileb.txt', 'dir1'])

By default, the files are not deleted, just removed from the inventory. To delete them from the filesystem as well:

wt.remove(['filea.txt', 'fileb.txt', 'dir1'], keep_files=False)

Renaming a File

You can change the name of a single file using WorkingTree.rename_one. You just provide the old and new names, e.g.:

wt.rename_one('oldfile.txt','newfile.txt')

Moving Files

You can move multiple files from one directory into another using WorkingTree.move:

wt.move(['olddir/file.txt'], 'newdir')

More complicated renames/moves can be done with transform.TreeTransform, which is outside the scope of this document.

Committing Changes

To commit _all_ the changes to your working tree you can just call the WorkingTree's commit method, giving it a commit message, e.g.:

wt.commit('this is my commit message')

To commit only certain files, you need to provide a list of filenames which you want to commit, e.g.:

wt.commit(message='this is my commit message', specific_files=['fileA.txt',
          'dir2/fileB.txt', 'fileD.txt'])

Generating a Log for a File

Generating a log is, in itself, simple. Grab a branch (see below) and pass it to show_log together with a log formatter, e.g.:

from bzrlib import log

b = Branch.open('/path/to/bazaar/branch')
lf = log.LongLogFormatter(to_file=sys.stdout)
log.show_log(b, lf)

Three log formatters are included with bzrlib: LongLogFormatter, ShortLogFormatter and LineLogFormatter. These provide long, short and single-line log output formats. It's also possible to write your own with very little code.

Annotating a File

To annotate a file, you want to walk every line of a file, retrieving the revision which last modified/created that line and then retrieving the information for that revision.

First get an annotation iterator for the file:

tree, relpath = WorkingTree.open_containing('/path/to/file.txt')
fileid = tree.path2id(relpath)
annotation = list(tree.annotate_iter(fileid))

To avoid repeatedly retrieving the same revisions, grab all revisions associated with the file together and build up a map of id to revision information. Also build a map of revision numbers, again indexed by the revision id:

revision_ids = set(revision_id for revision_id, text in annotation)
revisions = tree.branch.repository.get_revisions(revision_ids)
revision_map = dict(izip(revision_ids, revisions))
revno_map = tree.branch.get_revision_id_to_revno_map()

Finally, use your annotation iterator to walk the lines of the file, displaying the information from your revision maps as you go:

for revision_id, text in annotation :
    rev = revision_map[revision_id]
    revno = revno_map[revision_id]
    revno_string = '.'.join(str(i) for i in revno)
    print "%s, %s: %s" % (revno_string, rev.committer, text)

Working with branches

To work with a branch you need a branch object associated with your branch:

from bzrlib.branch import Branch

b = Branch.open('/home/jebw/bzrtest')

Branching from an existing branch

To branch you create a branch object representing the original branch, and supply a path/url to the new branch location. The following code clones the bzr.dev branch (the latest copy of the Bazaar source code) - be warned there is no feedback while it downloads the 60 mb associated with the branch:

b = Branch.open('http://bazaar-vcs.org/bzr/bzr.dev')
nb = b.bzrdir.sprout('/tmp/newBzrBranch').open_branch()

This provides no feedback, since Bazaar automatically uses the 'silent' UI.

Pushing and pulling branches

To push a branch, you need to open the source and destination branches, then call push with the other branch as a parameter:

b1 = Branch.open('file:///home/user/mybranch')
b2 = Branch.open('http://bazaar-vcs.org/bzr/bzr.dev')
b1.push(b2)

Pulling is similar:

b1.pull(b2)

If you have a working tree, as well as a branch, you should use WorkingTree.pull, not Branch.pull.

This '''won't''' handle conflicts automatically, so any conflicts will be left in the working tree for the user to resolve.

Checkout from an existing branch

This performs a Lightweight checkout from an existing Branch:

from bzrlib.bzrdir BzrDir

accelerator_tree, source = BzrDir.open_tree_or_branch('http:URL')
source.create_checkout('/tmp/newBzrCheckout', None, True, accelerator_tree)

To make a heavyweight checkout, change the last line to:

source.create_checkout('/tmp/newBzrCheckout', None, False, accelerator_tree)

History Operations

Finding the last revision number or id

To get the last revision number and id of a branch use:

revno, rev_id = branch.last_revision_info()

If all you care about is the revision id there is also the method:

rev_id = branch.last_revision()

Getting the list of revision ids that make up a branch

IMPORTANT: This should be avoided wherever possible, as it scales with the length of history:

rev_ids = branch.revision_history()

now rev_ids[0] is the revision id of the first commit, and rev_ids[-1] is the revision id of the most recent. Note that if all you want is the last revision id then you should use branch.last_revision() as described above, as it is much more efficient.

Getting a Revision object from a revision id

The Revision object has attributes like "message" to get the information about the revision:

repo = branch.repository
revision = repo.get_revision(rev_id)
print revision.message

Getting a revision id from a revision number

To get a revision id for a specific revision number use:

rev_id = branch.get_rev_id(revno)

Accessing the files from a revision

To get the file contents and tree shape for a specific revision you need a RevisionTree. These are supplied by the repository for a specific revision id:

revtree = repo.revision_tree(rev_id)

RevisionTrees, like all trees, can be compared as described in "Comparing Trees" above.

The most common way to list files in a tree is Tree.iter_entries(). The simplest way to get file content is Tree.get_file(). The best way to retrieve file content for large numbers of files Tree.iter_files_bytes()`

Loading plugins

To allow bzrlib to work with all plugins enabled you have to force it like this:

from bzrlib.plugin import load_plugins
load_plugins()

That code should be close to your "import bzrlib" to avoid problems.

To import a specific plugin you can do:

from bzrlib.plugins.someplugin import somemodule