closure = decorator?

[Piet van Oostrum]

Jussi Piitulainen <jpiitula at ling.helsinki.fi> writes:

> I don't actually know for sure what the most correct terminology is,
> but I like to think that a closure is a procedure (function) closed in
> the environment (namespace) where it was created, so even when it is
> called from another environment, it uses the one where it was born.

I usually say that a closure is a package, containing a function with
some additional data it needs. The data usually is in the form of name
bindings.

On the other hand, an object (instance) is a package containg data, with
one of more functions that work on this data.

So an object is more or less the dual of a closure, and in many cases
they can be used for the same purpose. In most programming languages the
difference is that closures can be called directly, whereas an object
needs to be used with a method call to do the same (this makes Java so
ugly in this area). In Python, however, you can define the __call__
method and with this they become almost identical in behaviour.
-- 
Piet van Oostrum <piet at vanoostrum.org>
WWW: http://pietvanoostrum.com/
PGP key: [8DAE142BE17999C4]