alternative to with statement?

Chris Kaynor ckaynor at zindagigames.com
Tue Feb 28 23:19:50 CET 2012


On Tue, Feb 28, 2012 at 1:04 PM, Craig Yoshioka <craigyk at me.com> wrote:
>
> I see that there was previously a PEP to allow the with statement to skip the enclosing block... this was shot down, and I'm trying to think of the most elegant alternative.
> The best I've found is to abuse the for notation:
>
> for _ in cachingcontext(x):
>    # create cached resources here
> # return cached resources
>
> I would have really liked:
>
> with cachingcontext(x):
>    # create cached resources here
> # return cached resources
>
> I'd also like to avoid the following because it is unnecessary boilerplate:
>
> with cachingcontext(x) as skip:
>    if not skip:
>         # create cached resources here
> # return cached resources
>

An alternative way to do this would be to make it a decorator.
Something along the lines of (written in my browser):

def cachedfunc(func):
    cachedvalue = None
    def newfunc(*args, **kwargs):
        nonlocal cachedvalue
        if cachedvalue is None:
            cachedvalue = func(*args, **kwargs)
        return cachedvalue
    return newfunc

@cachedfunc
def test():
    import time
    time.sleep(1)
    return 10

test() # should take 1 second
test() # should be instant

While that formula has limitations, it shows the basis of the idea.
I'll leave it to the reader to expand it to allow calls with different
arguments producing different results.

>
>
>
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