[Zope-CMF] RFC: browser views and memoization

[yuppie]

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.)


Cheers,

	Yuppie