hgext/pager.py

interfaces: add the optional `bdiff.xdiffblocks()` method

PyCharm flagged where this was called on the protocol class in `mdiff.py` in the
previous commit, but pytype completely missed it.  PyCharm is correct here, but
I'm committing this separately to highlight this potential problem- some of the
implementations don't implement _all_ of the methods the others do, and there's
not a great way to indicate on a protocol class that a method or attribute is
optional- that's kinda the opposite of what static typing is about.

Making the method an `Optional[Callable]` attribute works here, and keeps both
PyCharm and pytype happy, and the generated `mdiff.pyi` and `modules.pyi` look
reasonable.  We might be getting a little lucky, because the method isn't
invoked directly- it is returned from another method that selects which block
function to use.  Except since it is declared on the protocol class, every
module needs this attribute (in theory, but in practice this doesn't seem to be
checked), so the check for it on the module has to change from `hasattr()` to
`getattr(..., None)`.  We defer defining the optional attrs to the type checking
phase as an extra precaution- that way it isn't an attr with a `None` value at
runtime if someone is still using `hasattr()`.

As to why pytype missed this, I have no clue.  The generated `mdiff.pyi` even
has the global variable typed as `bdiff: intmod.BDiff`, so uses of it really
should comply with what is on the class, protocol class or not.

# pager.py - display output using a pager
#
# Copyright 2008 David Soria Parra <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
#
# To load the extension, add it to your configuration file:
#
#   [extension]
#   pager =
#
# Run 'hg help pager' to get info on configuration.

'''browse command output with an external pager (DEPRECATED)

Forcibly enable paging for individual commands that don't typically
request pagination with the attend-<command> option. This setting
takes precedence over ignore options and defaults::

  [pager]
  attend-cat = false
'''

from __future__ import annotations

from mercurial import (
    cmdutil,
    commands,
    dispatch,
    extensions,
    registrar,
)

# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = b'ships-with-hg-core'

configtable = {}
configitem = registrar.configitem(configtable)

configitem(
    b'pager',
    b'attend',
    default=lambda: attended,
)


def uisetup(ui):
    def pagecmd(orig, ui, options, cmd, cmdfunc):
        auto = options[b'pager'] == b'auto'
        if auto and not ui.pageractive:
            usepager = False
            attend = ui.configlist(b'pager', b'attend')
            ignore = ui.configlist(b'pager', b'ignore')
            cmds, _ = cmdutil.findcmd(cmd, commands.table)

            for cmd in cmds:
                var = b'attend-%s' % cmd
                if ui.config(b'pager', var, None):
                    usepager = ui.configbool(b'pager', var, True)
                    break
                if cmd in attend or (cmd not in ignore and not attend):
                    usepager = True
                    break

            if usepager:
                # Slight hack: the attend list is supposed to override
                # the ignore list for the pager extension, but the
                # core code doesn't know about attend, so we have to
                # lobotomize the ignore list so that the extension's
                # behavior is preserved.
                ui.setconfig(b'pager', b'ignore', b'', b'pager')
                ui.pager(b'extension-via-attend-' + cmd)
            else:
                ui.disablepager()
        return orig(ui, options, cmd, cmdfunc)

    extensions.wrapfunction(dispatch, '_runcommand', pagecmd)


attended = [b'annotate', b'cat', b'diff', b'export', b'glog', b'log', b'qdiff']