[Python-ideas] Fwd: argparse - add support for environment variables

[Miki Tebeka]

On Tuesday, February 19, 2013 8:29:48 PM UTC-8, Eli Bendersky wrote:
>
> On Tue, Feb 19, 2013 at 3:51 PM, Miki Tebeka <miki.... at gmail.com<javascript:>
> > wrote:
>
>>
>> Why not: 
>>>
>>>     parser.add_argument('--spam', default=os.environ.get('SPAM', 7)) 
>>>
>>  Mainly because then you can't swap in different dictionaries to resolve 
>> SPAM (when specifying "env" to ArgumentParser).
>>
>
> Can you elaborate on this requirement?
>

Sure. The idea is the you have some kind of "parameter resolution" (very 
much like the interpreter is resolving variables). You first look into the 
command line, and if not found you query a dictionary. Most times, this 
dictionary will be os.environ. However you can pass your own dictionary to 
resolve the parameters (for testing, configuration files). You can even use 
something like Raymonds Nested Contexts<http://code.activestate.com/recipes/577434-nested-contexts-a-chain-of-mapping-objects/>for that matter.
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