mercurial/txnutil.py

dispatch: don't show list of commands on bogus command

If a command is ambiguous, you get this:

  $ hg ve
  hg: command 've' is ambiguous:
      verify version
  [255]

If you typo a command, you get this:

  $ hg comit
  hg: unknown command 'comit'
  (did you mean one of commit, incoming, mycommit?)
  [255]

But if you completely mistype a command so it no longer looks like any
existing commands, you get a full list of commands. That might be
useful the first time you use Mercurial, but after that it's probably
more annoying than help, especially if you have the pager enabled and
have a short terminal. Let's instead give a short hint telling the
user to run `hg help` for more help.

Differential Revision: https://phab.mercurial-scm.org/D4024

# 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)