Passing temporaries as non-const references in C++

Question

I have the following piece of code, as an example dec_proxy attempts to reverse the effects of the increment operator upon the type that is executed in a complex function call f

Answer 1

What you try to do is to pass a rvalue (your new dec_facade(i)) as an lvalue reference, which explains why it doesn't work.

If you compiler support it, you can use rvalue references, using && type modifier : (Support for rvalue reference could be enabled by switching on C++0x or C++11 [partial] support)

template
void foo(T& t)
{    
    ++t;
}
template
void foo(T&& t)
{    
    ++t;
}

But that only one part of the problem. What you try to do, is to pre-increment a temporary value! That's non-sense, as it won't live after that call. Your object will be increment, then destroyed.

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One other solution would be to remove the & from your function definition, which would permit it to accept any parameter. But that's perhaps not what you want.