yuppie wrote:
Hi!
The skin scripts for complex forms in CMF like folder_contents are
currently big monolithic blocks of code. All the values needed in the
template are computed in a predefined order that makes sure expensive
tasks like querying the catalog or listing folder contents are performed
only once (per request).
Trying to convert this into a browser view and to split the code in
several methods I stumbled other the following issue:
If globally needed values are returned by their own method they have to
be computed again and again, although during the short live of a view
class they can be considered static.
One option would be to pre-compute those values in the __call__ method
and to store them in the view object. An other option is to cache the
results.
I ended up using this method as decorator for most methods:
def memoize(func):
memo = {}
def memoized_func(*args):
if args not in memo:
memo[args] = func(*args)
return memo[args]
return memoized_func
Are there better ways to resolve this?
Will those memo dicts be removed together with the view object or does
this create a potential memory leak? (I'm not very familiar with
decorators.)
that's pretty elegant compared to shoving a multitude of values into the
view. The closest thing to it would be a PEAK binding, but even that
can't handle the variety of situations that keing the memo by function
signature gives you. very nice.
that looks safe; as far as I can tell when the decorated method is
garbage collected with the view, all refs to 'memo' should be reaped..
In python 2.4 you could use frozenset to have keyword support too. I
think something like this would work:
> def memoize(func):
> memo = {}
> def memoized_func(*args, **kwargs):
> sig = (args, frozenset(kwargs.items()))
> if sig not in memo:
> memo[sig] = func(*args, **kwargs)
> return memo[sig]
> return memoized_func
-w
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