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deductiongu...td::function(3) C++ Standard Libarydeductiongu...td::function(3) NAME deductionguidesforstd::function - deductionguidesforstd::function Synopsis Defined in header <functional> template< class R, class... ArgTypes > (1) (since C++17) function( R(*)(ArgTypes...) ) -> function<R(ArgTypes...)>; template< class F > (2) (since C++17) function( F ) -> function</*see below*/>; 1) This deduction guide is provided for std::function to allow de- duction from functions. 2) This overload participates in overload resolution only if &F::op- erator() is well-formed when treated as an unevaluated operand and de- cltype(&F::operator()) is of the form R(G::*)(A...) (optionally cv-qualified, optionally noex- cept, optionally lvalue reference qualified) for some class type G. The deduced type is std::function<R(A...)>. Notes The type deduced by these deduction guides may change in a later standard revision (in particular, this might happen if noexcept support is added to std::function in a later standard). Example // Run this code #include <functional> int func(double) { return 0; } int main() { std::function f{func}; // guide #1 deduces function<int(double)> int i = 5; std::function g = [&](double) { return i; }; // guide #2 deduces function<int(double)> } Defect reports The following behavior-changing defect reports were applied retroac- tively to previously published C++ standards. DR Applied to Behavior as published Correct behavior LWG 3238 C++17 behavior of (2) was unclear clarified http://cppreference.com 2022.07.31 deductiongu...td::function(3)
NAME | Synopsis | Notes | Example
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