On Mon, 25 Apr 2005 16:48:46 -0400, Bill Mill wrote: > On 25 Apr 2005 23:33:48 +0300, Ville Vainio <[EMAIL PROTECTED]> wrote:
>> Still, list comprehensions should be implemented in terms of genexps to >> get rid of the LC variable that is visible outside the scope of the LC. >> >> > +1 . I think that we should still have the form [genexp] , but without the > dangling variable, and implemented with generator expressions. It seems to > me that it is inconsistent if I can do list(genexp) but not [genexp] , > since they are so similar. Once that happens, we can tell people who ask > the OP's question that [genexp] is just another way to spell list(genexp), > and he should use it if he wants the entire list constructed in memory. This is what I meant. Robert Kern says the implementations really differ, but I submit that is an accident of the order they were created in, not a fundamental constraint. list(genexp) works today and does almost exactly the same thing, minus an optimization or two that people are working on generalizing anyways, which is the right approach. I doubt that Python 3.0 would have two radically different implementations; they'll just have the genexp implementation, and an optimization for list creation if the list creation can know the size in advance, regardless of where it came from. >> Jeremy> should be relatively simple), it's not worth breaking that >> Jeremy> code. >> >> Well, the code that relies on the dangling variable deserves to break. > > Agreed. This is not what I meant and I agree with it too. Breaking code depending on variable leaking is one thing; breaking all code that uses list comprehensions is quite another. Just because 3.0 is going to break a lot of code anyhow doesn't mean we should be *gratuitous* about it! -- http://mail.python.org/mailman/listinfo/python-list
