[PATCH 01 of 14 RFC] dispatch: add ability to specify ipdb as a debugger

[Sean Farley]

mpm at selenic.com writes:

> On Tue, 2013-07-09 at 16:54 -0500, Sean Farley wrote:
>> # HG changeset patch
>> # User Sean Farley <sean.michael.farley at gmail.com>
>> # Date 1372876982 18000
>> #      Wed Jul 03 13:43:02 2013 -0500
>> # Node ID 2bda9c94e65cff8c6968d82cfc07ec6049b194c0
>> # Parent  648d1974b3f328947ee6cf2d00c66815a33cd208
>> dispatch: add ability to specify ipdb as a debugger
>> 
>> Question: is there a better way to test a module's availability with
>> demandimport?
>> 
>> diff --git a/mercurial/commands.py b/mercurial/commands.py
>> --- a/mercurial/commands.py
>> +++ b/mercurial/commands.py
>> @@ -37,11 +37,11 @@
>>      ('v', 'verbose', None, _('enable additional output')),
>>      ('', 'config', [],
>>       _('set/override config option (use \'section.name=value\')'),
>>       _('CONFIG')),
>>      ('', 'debug', None, _('enable debugging output')),
>> -    ('', 'debugger', None, _('start debugger')),
>> +    ('', 'debugger', 'pdb', _('start debugger')),
>
> Ok, so we're changing --debugger to accept an arg..
>
>> +    if '--debugger' in req.args:
>> +        debugger = 'pdb'
>> +    debugarg = _earlygetopt(['--debugger'], req.args)
>
> And then doing some special voodoo to allow it to not accept an arg?

Hmm, I thought that was how args were retrieved in dispatch.py? What is
usable in dispatch.py at this point in the code for getting an optional
argument?

> This is unfortunate. We've carefully avoided having optional args until
> now because they're stupidly complicated. And we can't have a mandatory
> arg to --debugger either.

Ah, I didn't realize there were no optional args.

> Btw, I don't see you using debugarg[1], so you've almost certainly got a
> bug here.

In the next line?

+    if debugarg:
+        debugger = debugarg[0]

Or was the "[1]" supposed to refer to something I missed?

> This might need to be an environment variable or (if possible) an hgrc
> setting.

Aha, that might indeed be a better idea. The question still remains on
how to check for an existence of a module with-in this demandimport
funny business?