On Wed, Jul 6, 2011 at 1:07 PM, Phlip <phlip2...@gmail.com> wrote:
> If I call m = md5() twice, I expect two objects.
>
> I am now aware that Python bends the definition of "call" based on
> where the line occurs. Principle of least surprise.
There is no definition-bending. The code:
"""
def file_to_hash(path, m = hashlib.md5()):
# do stuff...
file_to_hash(path1)
file_to_hash(path2)
"""
does not call hashlib.md5 twice. It calls it *once*, at the time the
file_to_hash function is defined. The returned object is stored on
the function object, and that same object is passed into file_to_hash
as a default value each time the function is called. See:
http://docs.python.org/reference/compound_stmts.html#function
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