view contrib/python-hook-examples.py @ 13751:85d74f6babf6

patch: deprecate ui.patch / external patcher feature

Why?
- Mercurial internal patcher works correctly for regular patches and git
  patches, is much faster at least on Windows and is more extensible.
- In theory, the external patcher can be used to handle exotic patch formats. I
  do not know any and have not heard about any such use in years.
- Most patch programs cannot handle git format patches, which makes the API
  caller to decide either to ignore ui.patch by calling patch.internalpatch()
  directly, or take the risk of random failures with valid inputs.
- One thing a patch program could do Mercurial patcher cannot is applying with
  --reverse. Apparently several shelve like extensions try to use that,
  including passing the "reverse" option to Mercurial patcher, which has been
  removed mid-2009. I never heard anybody complain about that, and would prefer
  reimplementing it anyway.

And from the technical perspective:
- The external patcher makes everything harder to maintain and implement. EOL
  normalization is not implemented, and I would bet file renames, if supported
  by the patcher, are not correctly recorded in the dirstate.
- No tests.

How?
- Remove related documentation
- Clearly mark patch.externalpatch() as private
- Remove the debuginstall check. This deprecation request was actually
  triggered by this last point. debuginstall is the only piece of code patching
  without a repository. When migrating to an integrated patch() + updatedir()
  call, this was really a showstopper, all workarounds were either ugly or
  uselessly complicated to implement. If we do not support external patcher
  anymore, the debuginstall check is not useful anymore.
- Remove patch.externalpatch() after 1.9 release.

'''
Examples of useful python hooks for Mercurial.
'''
from mercurial import patch, util

def diffstat(ui, repo, **kwargs):
    '''Example usage:

    [hooks]
    commit.diffstat = python:/path/to/this/file.py:diffstat
    changegroup.diffstat = python:/path/to/this/file.py:diffstat
    '''
    if kwargs.get('parent2'):
        return
    node = kwargs['node']
    first = repo[node].parents()[0].node()
    if 'url' in kwargs:
        last = repo['tip'].node()
    else:
        last = node
    diff = patch.diff(repo, first, last)
    ui.write(patch.diffstat(util.iterlines(diff)))