mercurial/txnutil.py

obsfate: add obsfate to default mapfile

Use the verbosity aware template keyword introduced earlier. It has the nice
property of being verbosity dependent but in order to customize the obsfate
part, users will need to replace the lobsfate definition from default mapfile
with the one using template functions (by copying the one from test-obsmarker-
template.t for example).

As it's a more advanced use-case, I'm more inclined to have the same code for
the {obsfate} keyword, in the changeset printer and in the default mapfile for
consistency.

But, the definition in default mapfile could be replaced with one based on
template filter to obsfate output customization if it is a big need for users.

# txnutil.py - transaction related utilities
#
#  Copyright FUJIWARA Katsunori <[e-mail]> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import errno

from . import (
    encoding,
)

def mayhavepending(root):
    '''return whether 'root' may have pending changes, which are
    visible to this process.
    '''
    return root == encoding.environ.get('HG_PENDING')

def trypending(root, vfs, filename, **kwargs):
    '''Open  file to be read according to HG_PENDING environment variable

    This opens '.pending' of specified 'filename' only when HG_PENDING
    is equal to 'root'.

    This returns '(fp, is_pending_opened)' tuple.
    '''
    if mayhavepending(root):
        try:
            return (vfs('%s.pending' % filename, **kwargs), True)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
    return (vfs(filename, **kwargs), False)