any_cast

[a.khawaldeh@…]

assume we have a class Base, and other class Derived that inherits Base.

I can write

boost::any a = new Derived;

so, the following code

Derived* d = any_cast<Derived*>(a);

will work good, but!!

Base* b = any_cast<Base*>(a);

will fail.

i.e boost::any_cast could not work with inheritance and polymorphism.

You may wonder why this is needed? but I did faced this case.

I solved this problem in boost::any on my machine, and I thought to share this with others, so if this sounds useful to you, please tell me how can I add my code to boost

many thanks.

[Antony Polukhin]

This is discussed at the ​following thread.

[Antony Polukhin]

The proposed implementation throws a held type and tries to catch it by base type. This is a quite curious technique!

Unfortunately it's not usable for production due to the exceptions being too heavy to throw and catch.