passing arguments

[Steve Holden]

Steven Bethard wrote:
> James Stroud wrote:
> 
>>import sys
>>
>>try:
>>  arg1 = sys.argv[1]
>>except IndexError:
>>  print "This script takes an argument, you boob!"
>>  sys.exit(1)
> 
> 
> Also possible, to guarantee that exactly one argument was given:
> 
> try:
>    arg1, = sys.argv
> except ValueError:
>    print "This script takes an argument, you boob!"
>    sys.exit(1)
> 
Aren't we forgetting argv[0] here, or am I overlooking something (like, 
you chopped it off without telling me?)?

Surely this would give an unpacking error if command-line arguments 
*were* present.

> If you want to get, say, 3 arguments, just change that line to:
> 
>    arg1, arg2, arg3 = sys.argv
> 
Similarly. Or are you just calling sys.argv[0] arg1 to confuse me? ;-)
> 
>>OR, way better: See the optparse module.
> 
> 
> Definitely.  Though depending on what kind of arguments your script 
> takes, you still may need to deal with the args that optparse returns.
> 
Anyway it's always good to know about the underlying mechanisms.

regards
  Steve
-- 
Steve Holden        +1 703 861 4237  +1 800 494 3119
Holden Web LLC             http://www.holdenweb.com/
Python Web Programming  http://pydish.holdenweb.com/