Pickling/unpickling extensions types

[Martin v. Löwis]

Bob <tenorman3 at yahoo.com> writes:

> In particular, what does this
> 
> "A callable object, which in the unpickling
> environment must be either a class, a callable
> registered as a ``safe constructor'' (see below), or
> it must have an attribute __safe_for_unpickling__ with
> a true value. Otherwise, an UnpicklingError will be
> raised in the unpickling environment. Note that as
> usual, the callable itself is pickled by name" 
> 
> mean?

What part of it is it that you don't understand? A "callable object"
is one that you can call. E.g. X is callable, if X(some_arguments)
"works":

>>> 1()
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
TypeError: 'int' object is not callable
>>> id(id)
1076510860

So the builtin id is callable, the number 1 is not. Examples for
callable objects are functions, bound methods, classes, and objects
whose classes implement __call__.

For "safe constructors", see below in the text.

"Have an attribute" means that getattr works. An object X has an
attribute y if X.y "works".

Regards,
Martin