[Python-Dev] argparse ambiguity handling (original) (raw)

Cameron Simpson cs at zip.com.au
Wed Apr 21 04:11:22 CEST 2010

On 20Apr2010 15:27, Neal Becker <ndbecker2 at gmail.com> wrote: | Steven Bethard wrote: || > On Tue, Apr 20, 2010 at 11:55 AM, Neal Becker <ndbecker2 at gmail.com> wrote: | >> I've noticed argparse ambiguity handling has changed a bit over last few | >> revisions. | >> | >> I have cases where 1 valid input is a prefix of another: | >> | >> e.g.: | >> '--string' | >> '--string2' | >> | >> With the most recent 1.1, the behavior is: | >> | >> --string=hello | >> | >> is accepted, while: | >> | >> --strin=hello | >> | >> is marked as ambiguous. | >> | >> I'm OK with this, but just want to know if there is agreement that this | >> is the behavior we want. | > | > I don't have a strong feeling about this. What was the behavior before? | > Steve || At least 1 earlier version said that even exact match was ambiguous. || I have a preference to allow at least exact matches to succeed even in the | case of ambiguity - mainly because I accidentally created this already once, | and I feel it's better to at least work somewhat. Not sure if there is any | more elegant solution. OTOH, I feel this is somewhat inelegant, as it | appears to treat exact match as a special case.

I think the new behaviour is desirable. Plenty of commands have both --foo and --foo-tweak. Usually because --foo came first and --foo-tweak came later, or simply because --foo is the simple and obvious and commonly wanted mode and --foo-tweak is a special case.

Real world example: rsync and the --delete* options. I'm sure plenty of others can be found.

The new behaviour makes this doable. The old behaviour made it unimplementable. Maybe it is desirable to be able to forbid this arguably-ambiguous option set, but I definitely feel that the current behaviour should be available.

Cheers,

Cameron Simpson <cs at zip.com.au> DoD#743 http://www.cskk.ezoshosting.com/cs/

If it wasn't for lawyers, we wouldn't need them.

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