Nested Function Question

Sat Jan 7 23:43:48 EST 2012

GZ於 2012年1月7日星期六UTC+8上午5時46分16秒寫道：
> Hi,
>> I am reading the documentation of functools.partial (http://
> docs.python.org/library/functools.html#functools.partial) and found
> the following 'reference implementation' of functools.partial.
>> def partial(func, *args, **keywords):
> def newfunc(*fargs, **fkeywords):
> newkeywords = keywords.copy()
> newkeywords.update(fkeywords)
> return func(*(args + fargs), **newkeywords)
> newfunc.func = func
> newfunc.args = args
> newfunc.keywords = keywords
> return newfunc
>> I don't understand why the below 3 lines are needed:
>> newfunc.func = func
> newfunc.args = args
> newfunc.keywords = keywords
>>> It is as if they are trying to prevent garbage collection, but I don't
> get why it is needed. As long as something holds reference to newfunc,
> because it in turn references keywords and args, nothing will be
> freed. If nothing is referencing newfunc, then everything should be
> freed.
>> Thanks,
> GZ

This is used to produce a new function with some default parameters fixed
of an old function that requires many parameters in the caller part. 