self modifying code

[Robin Becker]

Peter Otten wrote:
....
>>
>> def func(a):
>>      global func, data
>>      data = somethingcomplexandcostly()
>>      def func(a):
>>          return simple(data,a)
>>      return func(a)
>>
........
> 
> at the cost of just one object identity test whereas your func()
> implementation will do the heavy-lifting every time func() is called in the
> client (unless func() has by chance been invoked as lazymodule.func()
> before the import).

in the example code the heavy lifting, costly(), is done only once as 
the function that does it is overwritten. As pointed out it won't work 
as simply in a class. Memoisation could improve the performance of the 
normal case form of the function ie

def func(a):
     return simple(data,a)

but I guess that would depend on whether simple(data,a) is relatively 
expensive compared to the costs the memo lookup.
-- 
Robin Becker