setting variables in outer functions

Duncan Booth duncan.booth at invalid.invalid
Thu Nov 1 10:26:21 CET 2007


Hrvoje Niksic <hniksic at xemacs.org> wrote:

> In real-life code, closures are used to implement callbacks with
> automatic access to their lexical environment without the need for the
> bogus additional "void *" argument one so often sees in C callbacks,
> and without communication through global variables.  If the callbacks
> can access variables in the outer scope, it's only logical (and
> useful) for them to be able to change them.  Prohibiting modification
> reduces the usefulness of closures and causes ugly workarounds such as
> the avar[0] pattern.
> 

In real life code methods are used to implement callbacks with automatic 
access to their environment without the need for any C type hacks.

What is your point here? Python isn't C (or Javascript). If you have a 
function which takes a callback in Python you just pass it a bound method 
and you have all the context you want without resorting to ugly workrounds.



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