[PATCH 2 of 6] configitems: add an official API for extensions to register config item

[Yuya Nishihara]

On Thu, 29 Jun 2017 15:59:17 +0200, Pierre-Yves David wrote:
> On 06/29/2017 03:48 PM, Yuya Nishihara wrote:
> > On Tue, 27 Jun 2017 15:00:31 +0200, Pierre-Yves David wrote:
> >> # HG changeset patch
> >> # User Pierre-Yves David <pierre-yves.david at octobus.net>
> >> # Date 1497700100 -7200
> >> #      Sat Jun 17 13:48:20 2017 +0200
> >> # Node ID 944f8e3191e6fa37f27d52d3c94d1ef702408ae4
> >> # Parent  714ce79885e32305c45febf0da59b2ce2093967d
> >> # EXP-Topic config.register
> >> # Available At https://www.mercurial-scm.org/repo/users/marmoute/mercurial/
> >> #              hg pull https://www.mercurial-scm.org/repo/users/marmoute/mercurial/ -r 944f8e3191e6
> >> configitems: add an official API for extensions to register config item
> >>
> >> Extensions can have a 'configtable' mapping and use
> >> 'registrar.configitem(table)' to retrieve the registration function.
> >>
> >> This behave in the same way as the other way for extensions to register new
> >> items (commands, colors, etc).
> >>
> >> diff --git a/mercurial/configitems.py b/mercurial/configitems.py
> >> --- a/mercurial/configitems.py
> >> +++ b/mercurial/configitems.py
> >> @@ -13,6 +13,11 @@ from . import (
> >>       error,
> >>   )
> >>   
> >> +def loadconfigtable(ui, extname, configtable):
> >> +    """update config item known to the ui with the extension ones"""
> >> +    for section, items in  configtable.items():
> >> +        ui._knownconfig.setdefault(section, {}).update(items)
> > 
> > So this effectively updates the global configitems.coreitems, and that's
> > unavoidable since the passed ui is a temporary object.
> 
> Hum, yes good catch, we are missing some copying around here. However 
> you mention the ui being a temporary object can you elaborate a bit? 
> (I've some notion of the weird life cycle of UI object but I'm not sure 
> I follow you here.

extensions.loadall() is called with "lui", which can be a temporary copy of
the main "ui". "lui" exists for preloading repo hgrc in dispatch layer.