[Python-ideas] Modern language design survey for "assign and compare" statements

Rhodri James rhodri at kynesim.co.uk
Mon May 21 07:05:40 EDT 2018

On 19/05/18 01:54, Mike Miller wrote:
> In short, extend the "if/elif", "while", and comprehension to:
>      if pattern.search(data) as match:
>          …
>      while read_next_item() as value:
>          …

Thanks for the analysis, but I'm afraid I must disagree with your 
recommendation.  It was the thought I first had when Chris came out with 
his first draft of the PEP several months ago, but it's not enough to 
cope with my usual use cases.  What I normally want is the Python 
equivalent of:

   while ((v = get_something()) != INCONVENIENT_SENTINEL)

The condition expression itself is not what I want to capture; I need a 
subexpression, which the "as" syntax won't give me.

Rhodri James *-* Kynesim Ltd

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