view mercurial/txnutil.py @ 38738:faea9b1980d9

histedit: drop --no-backup option

Dropping this option because now we have a better option
than passing --no-backup flag every time, now user can
set a config in hgrc:

[ui]
history-editing-backup = False

This config aims to operate on every history editing command and
it is still work in progress. As yuya suggessted it probably to
late to add full support this config, so making this as
an experimental config.

Differential Revision: https://phab.mercurial-scm.org/D3965

# 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)