SWIG: Tie lifetime of object to a result

Oliver Tengler ot at matrix-vision.de
Fri Nov 14 09:12:37 CET 2003


Hi,

I wrap the following code with SWIG:

class Bar {};

class Foo
{
public:
	const Bar* getBar() { return &m_bar; }

	Bar m_bar;
};

'Foo::getBar' returns an internal reference to 'Bar' that is only
valid as long as 'Foo' is existing.
This raises a problem I am not able to solve using SWIG:

>>> f = mod.Foo()
>>> b = f.getBar()
>>> del f

After these lines 'b' is a dangeling pointer because 'f' has been
deleted.
My question is: How can I tie the lifetime of 'Foo' to that of 'Bar' ?

Boost.Python has a special keyword to solve this problem
("return_internal_reference").
Please give me some hints how to solve this using SWIG.

I already worked through the SWIG documentation and asked google but
with no results.

Thanks !

Regards,
Oliver Tengler




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