contrib/python-hook-examples.py

revset: store full detail into revsetalias.error for error source distinction

Before this patch, any errors in the declaration of revset alias
aren't detected at all, and there is no information about error source
in the error message.

As a part of preparation for parsing alias declarations and
definitions more strictly, this patch stores full detail into
"revsetalias.error" for error source distinction.

This makes raising "Abort" and warning potential errors just use
"revsetalias.error" without any message composing.

'''
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)))