En Wed, 14 Feb 2007 04:23:46 -0300, [EMAIL PROTECTED]
<[EMAIL PROTECTED]> escribió:
> I am OK with calls being stacked, but I wondering will the local
> variables be stacked given that return statement is followed by the
> function call?
>
> def test():
> x = 22
> y = 33
> z = x+y
> return anotherFunction(z)
>
> In this function will all the local variables (x,y,z) be pushed into
> the stack before calling anotherFunction(z) or Python will find out
> that the locals are no longer needed as anotherFunction(z) is just
> returned?
Not exactly like "pushed into the stack", but there exists a frame object,
and it contains references to its local variables, and will be alive until
anotherFunction returns. From inside anotherFunction you can even inspect
those variables:
py> def test():
... x = 22
... y = 33
... z = x+y
... return anotherFunction(z)
...
py> def anotherFunction(z):
... print "previous frame:", sys._getframe(1).f_locals
...
py> test()
previous frame: {'y': 33, 'x': 22, 'z': 55}
So x,y,z will still be there until anotherFunction actually returns to
test, and the frame object is disposed. For a highly recursive function,
that's bad news. For debugging normal programs, that's good news; the
cgitb module, by example, is able to show the values for local variables
in all previous frames when an exception is raised.
--
Gabriel Genellina
--
http://mail.python.org/mailman/listinfo/python-list
