Alternate implementation of default arguments: document in description and set post-argparse

[gdevenyi]

See comment here:
http://python.6.x6.nabble.com/argparse-tell-if-arg-was-defaulted-tp1528162p1528165.html

This means having unset defaults in argparse, and then setting the values after parsing by checking for none.

I think this would resolve the chunk_size and ppj metaprogramming, my issues with the list appending, and possible other magics in a saner way.

Thoughts?

[pipitone]

I considered this, but then the default isn't shown in the help. We could write it into the help ourselves, I suppose.

[gdevenyi]

That's what my thought was. I think that would make the code quite a bit cleaner.

[pipitone]

That's what my thought was. I think that would make the code quite a bit cleaner.

Ah, I see now you had this idea in the issue title. :-)

[pipitone]

I'm good with this.