contrib/python-hook-examples.py

zope: force module import by importing symbols

Previously, we tried to import a module and handle the ImportError.
Our lazy module importer doesn't verify the module exists and returns
a dummy object representing the module. Only once we attempt to load
a symbol in the module does the ImportError get raises.

This means that simple imports inside `try..except ImportError` don't
detect missing modules.

This commit changes imports in zope.interface to access symbols, thus
forcing module load and triggering ImportError.

This fixes zope.interface for pure builds.

Differential Revision: https://phab.mercurial-scm.org/D2980

'''
Examples of useful python hooks for Mercurial.
'''
from __future__ import absolute_import
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)))