[Python-Dev] "as" mania

[Alex Martelli]

On Mar 7, 2006, at 6:15 AM, Georg Brandl wrote:

> Hi,
>
> while "as" is being made a keyword, I remembered parallels between  
> "with"
> and a proposal made some time ago:
>
> with expr as f:
>     do something with f
>
> while expr as f:
>     do something with f
>
> if expr as f:
>     do something with f
> elif expr as f:
>     do something else with f
>
> What do you think?

I think the best use cases for 'assignment inside an if or while'  
condition, as far as they go, require `capturing' a SUB-expression of  
the condition, rather than the whole condition.  E.g., in C,

while ( (x=next_x()) < threshold ) ...

being able to capture (by `as') only the whole (true or false)  
condition meets a minority of the use cases, so I'm unenthusiastic  
about it.


Alex