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[Python-Dev] New PEP

Ethan Furman ethan at stoneleaf.us
Thu Mar 22 01:09:22 CET 2012 
Huan Do wrote:
> *Hi,
> 
> I am a graduating Berkeley student that loves python and would like to 
> propose an enhancement to python. My proposal introduces a concept of 
> slicing generator. For instance, if one does x[:] it returns a list 
> which is a copy of x. Sometimes programmers would want to iterate over a 
> slice of x, but they do not like the overhead of constructing another 
> list. Instead we can create a similar operator that returns a generator. 
> My proposed syntax is x(:). The programmers are of course able to set 
> lower, upper, and step size like the following.
> 
> x(1::-1)

The biggest problem with your proposal is that generators don't remember 
what they have already yielded, so

x(:) != x(:) # first time gets everything, second time gets nothing

~Ethan~
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