Getting a set of lambda functions

[Denis Kasak]

On Sun, May 25, 2008 at 1:43 PM, Martin Manns <mmanns at gmx.net> wrote:
> Hi,
>
> I try to get a set of lambda functions that allows me executing each
> function code exactly once. Therefore, I would like to modify the set
> function to compare the func_code properties (or the lambda
> functions to use this property for comparison).
>
> (The reason is that the real function list is quite large (> 1E5), there
> are only few functions with non-equal code and the order of execution
> is not important.)
>
> How can I achieve this?
>
>>>> func_strings=['x', 'x+1', 'x+2', 'x']
>>>> funclist = [eval('lambda x:' + func) for func in func_strings]
>>>> len(funclist)
> 4
>>>> len(set(funclist))
> 4
>>>> funclist[0].func_code == funclist[3].func_code
> True
>>>> funclist[0] == funclist[3]
> False

Isn't this a bug? Shouldn't it be possible to create a set of
different lambda functions via a loop? At first I thought it was just
a quirk of list comprehensions, but the following example also yields
incorrect (or at least unintuitive) results:

>>> spam = []
>>> for i in range(10):
...   spam.append(lambda: i)
>>> spam[0]()
9
>>> spam[1]()
9

Manually creating the lambdas and appending them to a list works as
expected, naturally; I don't see a good reason why it wouldn't work
with a loop. Am I missing something?

--
Denis Kasak