Question

Using Boost.Python, is there a way to call a Python function that’s been passed through a weakref? The following code doesn’t work:

import weakref

def foo():
    print 'it works'

def func():
    return weakref.ref(foo)

The following is the C++:

object module = import("test");
object func(module.attr("func"));
object foo = func();
foo(); // Should print 'it works', but it prints nothing

However, if I pass the function object without weakref, it all works fine. Is there any way to make this work?

Answer 1

From weakref documentation:

Return a weak reference to object. The original object can be retrieved by calling the reference object if the referent is still alive…

So, given your snippet:

import weakref

def foo():
    print "It Works!"

def func():
    return weakref.ref(foo)

ref = func() # func returns the reference to the foo() function
original_func = ref() # calling the reference returns the referenced object
original_func() # prints "It Works!"