[PATCH 07 of 11 V2] ui: use scmutil.rccomponents to load configs (BC)

[Jun Wu]

Excerpts from Ryan McElroy's message of 2017-03-22 11:37:00 +0000:
> On 3/22/17 7:50 AM, Jun Wu wrote:
> > # HG changeset patch
> > # User Jun Wu <quark at fb.com>
> > # Date 1489462886 25200
> > #      Mon Mar 13 20:41:26 2017 -0700
> > # Node ID add83f47bf3a51edbd58aa0fb6e571d186bdae6e
> > # Parent  df768455486ff51b4047fd3a8dfbef158516d2aa
> > ui: use scmutil.rccomponents to load configs (BC)
> >
> > This is BC because system configs won't be able to override $EDITOR, $PAGER.
> > The new behavior is arguably more rational.
> >
> > diff --git a/mercurial/ui.py b/mercurial/ui.py
> > --- a/mercurial/ui.py
> > +++ b/mercurial/ui.py
> > @@ -212,6 +212,18 @@ class ui(object):
> >           u = cls()
> >           # we always trust global config files
> > -        for f in scmutil.rcpath():
> > -            u.readconfig(f, trust=True)
> > +        for (t, f) in scmutil.rccomponents():
> > +            if t == 'path':
> > +                u.readconfig(f, trust=True)
> > +            elif t == 'items':
> > +                sections = set()
> > +                for section, name, value, source in f:
> > +                    # do not set ocfg
> > +                    u._tcfg.set(section, name, value, source)
> > +                    u._ucfg.set(section, name, value, source)
> > +                    sections.add(section)
> > +                for section in sections:
> > +                    u.fixconfig(section=section)
> > +            else:
> > +                raise error.ProgrammingError('unexpected rccomponent: %s' % t)
> >           return u
> 
> Seeing this makes me not like this "union type" (rccomponents) that 
> you've created. Can we do this differently for more cleanliness?

The code here is temporary and will be rewritten once the immutable config
becomes a thing.  I will add a comment but not rewrite the temporary code.

> Consider instead of having rccomponents be a parsed config "source" 
> (either a file or environment for now). Then this patch simply combines 
> them in order. This gives us the nice property of reading each config 
> file only once, which was a patch series that dsop sent but had BC 
> issues, but doing it this way means there are no BC issues. Of course, 
> it also cleans up this code so we don't have the type check in there.

If I understand what you suggest, I think it could have issues with
"%unset".

Although that may be solved, but the immutable config will be a thing, so
I'm not interested in improving to-be-deprecated code.

> Essentially, envconfig() can be generalized into a "parsedconfig" 
> container, and then it's just about ordering for the final config from 
> there.
> 
> I think this would make the code cleaner -- thoughts?
> 
> >   
> > diff --git a/tests/test-config-env.py b/tests/test-config-env.py
> > new file mode 100644
> > --- /dev/null
> > +++ b/tests/test-config-env.py
> > @@ -0,0 +1,48 @@
> > +# Test the config layer generated by environment variables
> > +
> > +from __future__ import absolute_import, print_function
> > +
> > +import os
> > +
> > +from mercurial import (
> > +    encoding,
> > +    scmutil,
> > +    ui as uimod,
> > +)
> > +
> > +testtmp = encoding.environ['TESTTMP']
> > +
> > +# prepare hgrc files
> > +def join(name):
> > +    return os.path.join(testtmp, name)
> > +
> > +with open(join('sysrc'), 'w') as f:
> > +    f.write('[ui]\neditor=e0\n[pager]\npager=p0\n')
> > +
> > +with open(join('userrc'), 'w') as f:
> > +    f.write('[ui]\neditor=e1')
> > +
> > +# replace rcpath functions so they point to the files above
> > +def systemrcpath():
> > +    return [join('sysrc')]
> > +
> > +def userrcpath():
> > +    return [join('userrc')]
> > +
> > +scmutil.systemrcpath = systemrcpath
> > +scmutil.userrcpath = userrcpath
> > +os.path.isdir = lambda x: False # hack: do not load default.d/*.rc
> > +
> > +# utility to print configs
> > +def printconfigs(env):
> > +    encoding.environ = env
> > +    scmutil._rccomponents = None # reset cache
> > +    ui = uimod.ui.load()
> > +    for section, name, value in ui.walkconfig():
> > +        source = ui.configsource(section, name)
> > +        print('%s.%s=%s # %s' % (section, name, value, source))
> > +    print('')
> > +
> > +# environment variable overrides
> > +printconfigs({})
> > +printconfigs({'EDITOR': 'e2', 'PAGER': 'p2'})
> > diff --git a/tests/test-config-env.py.out b/tests/test-config-env.py.out
> > new file mode 100644
> > --- /dev/null
> > +++ b/tests/test-config-env.py.out
> > @@ -0,0 +1,6 @@
> > +pager.pager=p0 # $TESTTMP/sysrc:4
> > +ui.editor=e1 # $TESTTMP/userrc:2
> > +
> > +pager.pager=p2 # $PAGER
> > +ui.editor=e1 # $TESTTMP/userrc:2
> > +
> > diff --git a/tests/test-config.t b/tests/test-config.t
> > --- a/tests/test-config.t
> > +++ b/tests/test-config.t
> > @@ -165,2 +165,16 @@ edit failure
> >     abort: edit failed: false exited with status 1
> >     [255]
> > +
> > +config affected by environment variables
> > +
> > +  $ EDITOR=e1 VISUAL=e2 hg config --debug | grep 'ui\.editor'
> > +  $VISUAL: ui.editor=e2
> > +
> > +  $ VISUAL=e2 hg config --debug --config ui.editor=e3 | grep 'ui\.editor'
> > +  --config: ui.editor=e3
> > +
> > +  $ PAGER=p1 hg config --debug | grep 'pager\.pager'
> > +  $PAGER: pager.pager=p1
> > +
> > +  $ PAGER=p1 hg config --debug --config pager.pager=p2 | grep 'pager\.pager'
> > +  --config: pager.pager=p2
> >