En Wed, 28 Jan 2009 18:06:01 -0200, Peter Otten <__pete...@web.de>
escribió:
Gabriel Genellina wrote:
(I think this has to do with free variables in the "right side" (after
the "in" keyword) of a generator expression; they appear to be evaluated
when the expression is *defined*, not when is is *used*. By contrast,
free
variables in the "left side" appear to be evaluated when the expression
is
used.)
Indeed, the right side is evaluated in the enclosing namespace and then
passed as an argument to the genexpr:
>>> dis.dis(compile("(x for y in z)", "nofile", "exec"))
1 0 LOAD_CONST 0 (<code object <genexpr> at
0x2b22b2dcf828, file "nofile", line 1>)
3 MAKE_FUNCTION 0
6 LOAD_NAME 0 (z)
9 GET_ITER
10 CALL_FUNCTION 1
13 POP_TOP
14 LOAD_CONST 1 (None)
17 RETURN_VALUE
Yes, this is explained (in not so much detail) in the Language Reference.
Now I *know* how it works, but still isn't *obvious* to me.
--
Gabriel Genellina
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