[Distutils] Missing options for setuptools develop

[Jamie Kirkpatrick]

Couple of things.

Currently there is no way to pass custom options through setuptools  
"develop" to distutils build_ext.  What this means in practice is  
that you cannot do the following things:

• pass the --debug flag to build_ext so as to have your module build  
against debug libraries.
• pass any of the SWIG options through.
• I'm sure there are other limitations.

Because of this I ended up abandoning the swig functionality of  
distutils and running that as a pre distuils phase of my build  
scripts - it would be better If I could use it through distutils  
though.  The show stopper is the fact I can't build against debug  
libraries - this means I cannot mix the --debug type builds and the  
develop functionality, something that seems like a logical thing to do.

Is there any chance that someone could find a way to allow options to  
be passed through to build_ext as it is run?  I'm sure its just a  
case of adding another option to setuptools develop and then passing  
it through at the relevant point.  If noone wants to take it on I'm  
happy to write a patch if we all agree its the way to go.

Thanks in advance

Jamie