En Fri, 20 Feb 2009 16:49:21 -0200, Alan Isaac <ais...@american.edu>
escribió:
I have a class `X` where many parameters are set
at instance initialization. The parameter values
of an instance `x` generally remain unchanged,
but is there way to communicate to a method that
it depends only on the initial values of these parameters
(and does not need to worry about any changes)?
The behavior of method `m` depends on these parameter values.
It turns out `m` gets called a lot, which means
that the pameter values are accessed over and over
(self.p0, self.p1, etc). I would like to
manufacture a function equivalent to the method
that simply uses fixed values (the values at the
time it is manufactured). I do not care if this
function is attached to `x` or not.
Not automatically; but you could refactor the method to call an external
function with arguments:
class X(...):
...
def foo(self):
c = self.a + self.b
return c
Rewrite the method as:
def foo(self):
return _foo(self.a, self.b)
and define _foo outside the class:
def _foo(a, b):
c = a + b
return c
If you want a "frozen" function (that is, a function already set-up with
the parameters taken from the current values of x.a, x.b) use
functools.partial:
x = X()
frozen_foo = functools.partial(_foo, a=x.a, b=x.b)
frozen_foo() # equivalent to x.foo() at the time it was defined
But if you call this in a loop, perhaps it's enough to assign x.a, x.b to
local variables and call _foo with those arguments.
--
Gabriel Genellina
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