Re: [boost] [mpl] is_macro_called

Subject: Re: [boost] [mpl] is_macro_called
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2010-04-03 16:44:07

AMDG

Lorenzo Caminiti wrote:
> Is there a way I can check at compile-time and class-scope if a macro
> has been called and expanded (at least one time) from within a member
> function?
>
> For example:
>
>     #define X(...) ... // Some macro definition -- the macro
> parameters could be anything needed to implement is_macro_called.
>
>     struct is_macro_X_called { ... }; // Some implementation -- this
> could be a template or something else.
>
> So that:
>
>     struct z {
>         void f() {
>             X(...); // Macro called from within a member function.
>         }
>
>         // Detect at class-scope and a compile-time that the macro was called.
>         static const bool is_macro_X_called::value; // Evaluates to true.
>     };
>
> Instead:
>
>     struct z {
>         void f() {
>             // X(...); // Macro not called.
>         }
>
>         static const bool is_macro_X_called::value; // Evaluates to false.
>     };
>
> I do not know how to program this. However, could for example the
> macro X() instantiate a template with some special template parameter
> that can then be inspected at compile-time by a is_macro_called
> metafunction?
>   

How do you prevent someone from defining the member function
out of line?  Even if you could do it, it seems prone to subtle bugs.

In Christ,
Steven Watanabe