Re: Making functions callable

On Wed, Mar 26, 2014 at 5:53 PM, Anthony <lifesillusion@gmail.com> wrote:
> I've yet to test it but I read a few people stating to use lambdas
> variables/properties. Is it definitely the case that it will only evaluate
> once?


from the python docs (2.7):

Default parameter values are evaluated when the function definition is
executed. This means that the expression is evaluated once, when the
function is defined, and that the same "pre-computed" value is used
for each call. This is especially important to understand when a
default parameter is a mutable object, such as a list or a dictionary:
if the function modifies the object (e.g. by appending an item to a
list), the default value is in effect modified. This is generally not
what was intended. A way around this is to use None as the default,
and explicitly test for it in the body of the function.

--
Javier

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