"as" keyword woes

Steven D'Aprano steve at REMOVE-THIS-cybersource.com.au
Tue Dec 9 14:24:32 CET 2008

On Tue, 09 Dec 2008 04:39:55 -0800, Paul Boddie wrote:

> To be fair to the complainant, before mentioning the GIL, he did
> initially get the usual trite fragments of the Zen of Python right back
> at him ("simple is better than complex", "special cases aren't special
> enough to break the rules"), albeit not the whole thing in its overused,
> unabridged form. I think I'd go on a rant if presented with that rather
> than the accepted reason for the noted shortcomings of the language:
> CPython's parsing technology isn't "sufficiently powerful parser
> technology" as GvR himself says [1].
> Paul
> [1]
> http://mail.python.org/pipermail/python-dev/2008-December/084023.html

That is not what Guido said. What he actually said was:

"That's possible with sufficiently powerful parser technology, but
that's not how the Python parser (and most parsers, in my experience)
treat reserved words."

In other words, with a more powerful parser, it would be POSSIBLE. But 
that doesn't mean that the only reason Python doesn't do what the OP 
wants is the lack of such a parser. To give an analogy: with sufficiently 
powerful automotive technology, we could all have cars capable of 
accelerating from 0 to 300mph in less than five seconds. (That's faster 
than the space shuttle accelerates, by the way.) The technology exists: 
drag racers have it. But the costs (financial and social) would be 
prohibitive, and so very few people have such cars, and those that do 
have restrictions on where and when they can use them.

What Guido is saying is that even if he agreed with the OP he couldn't 
add that feature. He's not saying that he agrees with the OP. The Zen 
gives good reasons for believing that even if Python's parser was 
sufficiently powerful, he'd still consider the feature undesirable.


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