How can I understan the "for" here?

[James Mills]

On Fri, Dec 12, 2008 at 12:44 AM, Kermit Mei <kermit.mei at gmail.com> wrote:
> I can't understand the second sentence because of the "for ... in".
> I consider that the syntactics of "for" should be:
>
> for k,v in params.items():
>   ......
>
> But there's no a colon here, why it can work?

It's called a list comprehension.
The "for x in y" construct becomes an expression.

Simple example:

Build a list of integers divisible by 3:

>>> [x for x in xrange(10) if not x % 3]
[0, 3, 6, 9]


cheers
James

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-- "Problems are solved by method"