[PATCH RFC] ui: add support for a tweakdefaults knob

[Augie Fackler]

> On Jun 15, 2017, at 11:19, Yuya Nishihara <yuya at tcha.org> wrote:
> 
> On Wed, 14 Jun 2017 21:37:21 -0400, Augie Fackler wrote:
>> # HG changeset patch
>> # User Augie Fackler <augie at google.com>
>> # Date 1497488194 14400
>> #      Wed Jun 14 20:56:34 2017 -0400
>> # Node ID 0e5ea7a86a8021d02218c35b07366ac6081ab3fb
>> # Parent  3abba5bc34546951b11b1bd3f5e5c77b90d950d1
>> ui: add support for a tweakdefaults knob
> 
> +1
> 
>> +    def _maybetweakdefaults(self):
>> +        if not self.configbool('ui', 'tweakdefaults'):
>> +            return
>> +        if self._tweaked or self.plain('tweakdefaults'):
>> +            return
>> +
>> +        # Note: it is SUPER IMPORTANT that you set self._tweaked to
>> +        # True *before* any calls to setconfig(), otherwise you'll get
>> +        # infinite recursion between setconfig and this method.
>> +        #
>> +        # TODO: We should extract an inner method in setconfig() to
>> +        # avoid this weirdness.
>> +        self._tweaked = True
>> +        tmpcfg = config.config()
>> +        tmpcfg.parse('<tweakdefaults>', tweakrc)
>> +        for section in tmpcfg:
>> +            for name, value in tmpcfg.items(section):
>> +                if not self.hasconfig(section, name):
>> +                    self.setconfig(section, name, value, "<tweakdefaults>")
> 
> Maybe we want tmpcfg -> {ucfg, tcfg} -> ocfg layers, but it wouldn't be
> doable right now since tmpcfg should be inserted *after* [uto]cfg are
> loaded.

Yeah. Nobody seems motivated enough to do that work, which I totally get, so I did "done" instead of "clean". If it ever gets to be enough of a pain we can refactor, and we can maybe fix it up if we ever redo configuration to be a stack of immutable objects.