Optional arguments

[Martin Pool]

On 12 Jul 2006, Aaron Bentley <aaron.bentley at utoronto.ca> wrote:
> On a related note:
> 
> I've got a command (bzrtools shove) that would like to do
> TAKES_ARGS=['source?', 'target']
> 
> The behaviour would be:
> 
> [] => ERROR
> ['TAR'] => {'target': 'TAR'}
> ['SRC', 'TAR'] => {source:'SRC', target:'TAR'}
> 
> Do you think that permitting optional arguments to occur before required
> arguments makes sense?  I've currently solved this by taking arguments
> in the reverse order: takes_args = ['target', 'source?'], but this isn't
> intuitive since it's different from commands such as branch.
> 
> The other option would be to change the command, so that you can omit an
> argument when it's run in the target directory, not the source.

I think it's reasonable to support such a syntax; there are other
commands that give a precedent.  There is already support in
_match_argform for an argument that repeats at least one, but not the
last argument.   So you could add one like that.

-- 
Martin