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From: Phillip Hellewell (sshock_at_[hidden])
Date: 2006-08-18 14:27:52


When using overloaded functions with shared_ptr parameter, overload
resolution is often ambigous. It is ambigous in situations where
using raw pointers would not be ambigous.

I've seen a few workarounds. One workaround is to make one of the two
functions a template function, but that does not work in all cases.
Another workaround is to just give the functions different names, but
you can't do that when the function is a CTOR.

Well, to my surprise, I found a post from Artyom Borodkin from last
December that explains how it can be permanently fixed in boost
itself! I thought there was no way I would ever resolve this.

I went ahead and tested his suggestion by modifying the boost source
(I had to change slightly what he wrote), and it worked!

I changed this constructor:

    template<class Y>
    shared_ptr(shared_ptr<Y> const & r): px(r.px), pn( // never throws

to this:

    template<class Y>
    shared_ptr(shared_ptr<Y> const & r, typename enable_if<typename
is_convertible<Y*, T*>::type, void*>::type = 0): px(r.px), pn( //
never throws

So to iterate what Artyom said, why would we not want to do this?!

Phillip Hellewell

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