view contrib/python-hook-examples.py @ 19932:e3a5922e18c3

demandimport: support "absolute_import" for external libraries (issue4029)

Before this patch, demandimport of Mercurial may fail to load external
libraries using "from __future__ import absolute_import": for example,
importing "foo" in "bar.baz" module will load "bar.foo" if it exists,
even though "absolute_import" is enabled in "bar.baz" module.

So, extensions for Mercurial can't use such external libraries.

This patch saves "level" of import request for on-demand module
loading in the future: default value of level is -1, and level is 0
when "absolute_import" is enabled.

"level" value is passed to built-in import function in
"_demandmod._load()" and it should load target module correctly.

This patch changes only one "_demandmod" construction case other than
cases below:

    - construction in "_demandmod._load()"

      this code path should be used only in relative sub-module
      loading case

    - constructions other than patched one in"_demandimport()"

      these code paths shouldn't be used in "level != -1" case

'''
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].p1().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)))