New configuration module released - command line options

Vinay Sajip vinay_sajip at red-dove.com
Thu Nov 4 00:58:26 CET 2004


Neal Becker wrote:

> The point is, you would like to specify the options once, and use this
> single specification for all option sources - instead of redundantly having
> to specify that there is a 'verbosity' option that takes a value of 'int'
> and has a default of 'whatever', and do this once (and with different
> syntax) for each source - config files, command line, etc.

The optparse module is very good for parsing command line options, but 
is not a general purpose program configuration facility. It's not really 
sensible to grow optparse to become a general purpose program 
configuration module.

The config module aspires to be a good configuration facility, but does 
not concern itself with parsing command line options. There's little 
point in reinventing the wheel when optparse is more than fit for 
purpose, for many people.

Hence, the best option is to make them work together, but it's unlikely 
that you'll get a 'one size fits all'. For example, some applications 
will allow a user to specify which configuration to load via command 
line options. In theory, a configuration file could be used to configure 
command line options and you could call optparse with those. But it's 
chicken and egg in many scenarios, and command line options for a 
program tend to be less volatile than configurations in general. I think 
it's more natural to specify configurations in a configuration file, and 
allow overriding some subset of them via command-line arguments.

I've posted (in another post) an example of how config and optparse can 
work together with  minimal fuss.

Best regards,


Vinay Sajip



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