Обходной путь для «использования переменной перед вычетом auto» ⇐ C++

[Гость]

I am creating wrapper functions, that modify existing functions (targets). The targets are determined at runtime as pointers without type information (

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void*

). Each of them has different parameters and return type. The wrapped functions are called from external code, so they have to match the signature of the target.

The basic scheme is like this:

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bool wrap(void* f, void** t) {     *t = magic();  // target determined at runtime as void*     return true; } // define new wrapping function and storage for target int(*foo_target)(int); int foo(int data) {     return foo_target(data) + 10; } auto res = wrap(reinterpret_cast(&foo), reinterpret_cast(&foo_target)); 

The

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wrap

function is a placeholder, that does all the heavy lifting. For each target I define a wrapper function (

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foo

) and a variable to store the function pointer to the target function with the correct type (

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foo_target

).

This works, but requires ugly type casts and I have to keep the signatures of

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foo_target

and

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foo

in sync manually. What I would like to have is something like this:

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template  struct wrap {     F* target;     wrap(F&& f)     {         target = reinterpret_cast(magic());     } }; static auto foo = wrap(     [](int data) -> int   //  int        // 

Источник: [url]https://stackoverflow.com/questions/78128208/workaround-for-use-of-variable-before-deduction-of-auto[/url]