yield_all needed in Python

Duncan Booth duncan.booth at invalid.invalid
Tue Mar 1 18:48:57 CET 2005


Douglas Alan wrote:

> "Terry Reedy" <tjreedy at udel.edu> writes:
> 
>> Cetainly, if <yield_all
>> iterator> == <for i in iterator: yield i>, I don't see how anything
>> is gained except for a few keystrokes.
> 
> What's gained is making one's code more readable and maintainable,
> which is the one of the primary reasons that I use Python.

On of the reasons why Python is readable is that the core language is 
comparatively small. Adding a new reserved word simply to save a few 
characters is a difficult choice, and each case has to be judged on its 
merits, but it seems to me that in this case the extra syntax is a burden 
that would have to be learned by all Python programmers with very little 
benefit.

Remember that many generators will want to do slightly more than just yield 
from another iterator, and the for loop allows you to put in additional 
processing easily whereas 'yield_all' has very limited application e.g.

   for tok in tokenstream():
       if tok.type != COMMENT:
           yield tok

I just scanned a random collection of my Python files: out of 50 yield 
statements I found only 3 which could be rewritten using yield_all.



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