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Simon Weber
2013-04-03 23:24:02 -04:00
parent c7f1da22a2
commit e1b5968857
1 changed files with 4 additions and 3 deletions
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docs/writing/gotchas.rst
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@@ -128,11 +128,12 @@ What Does Happen
Five functions are created, but all of them just multiply ``x`` by 4.
Python's closures are *late binding*. This means that names within closures are
looked up at the time the inner function is *called*.
Python's closures are *late binding*.
This means that the values of variables used in closures are looked
up at the time the inner function is called.
Here, whenever *any* of the returned functions are called, the value of ``i``
is looked up in the surrounding scope at call time, when by then the loop has
is looked up in the surrounding scope at call time. By then, the loop has
completed and ``i`` is left with its final value of 4.
What's particularly nasty about this gotcha is the seemingly prevalent