[Python-Dev] PEP 289 - Generator Expressions (original) (raw)

[Python-Dev] PEP 289 - Generator Expressions - Let's Move Forward

Guido van Rossum guido at python.org
Fri Apr 30 19:12:59 EDT 2004

I was using this example more generally to show that if you have a late-binding genexpr, you have to worry about not changing the local variables it uses, which looks like all uses of genexprs with free variables are subtle bugs waiting to appear whenever someone modifies the function anywhere after the genexpr. The same argument applies to the other stdlib cases I mentioned (which make somewhat less than 10% of all uses).

That's not new, we all know that that's the downside of late binding.

My counter to that is that any use of genexps where the consumer doesn't consume (or discard) the iterator before the next line is reached is extremely advanced use.

--Guido van Rossum (home page: http://www.python.org/~guido/)

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