[Python-Dev] PEP 389: argparse - new command line parsing module

[Nick Coghlan]

Barry Warsaw wrote:
> On Sep 29, 2009, at 8:25 PM, Nick Coghlan wrote:
> 
>> getopt is very procedural - you define a minimal amount regarding the
>> options you accept, but then do the bulk of the command line processing
>> yourself
> 
> Right, and we shouldn't underestimate the cognitive load this imposes. 
> All those twisty if-conditions are de-facto part of getopt's API.

People assess the mental cost differently though - for getopt, they tend
to assign the cost to the script they're currently writing, while for
optparse/argparse they assign the cost to those two libraries being
difficult to learn :)

Keeping getopt around *and* including a "add_getopt_arguments" method in
argparse is probably the best of both worlds, in that it allows for
relatively straightforward evolution of an application:

1. Start with getopt
2. As the getopt argument parsing gets twisty and arcane and maintaining
the help string becomes a nightmare, move to argparse with the
"add_getopt_arguments" method.
3. Over time, convert more arguments to proper argparse arguments with
full documentation.

(Note that getting a good help string "for free" is one of the biggest
gains I currently find in using optparse over getopt. This is especially
so once you start making use of option groups)

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
---------------------------------------------------------------