Conversion Member Templateを使った戻り値型の指定の省略

C++ Grammar
  • 一時的なクラスを用意して、戻り値の型の指定を省略できるようにする
  • 使いどころが多くて面白いです・・・参照
  • xxx_castのような関数にも全部用意してはどうだろう・・・boost::lexical_castの場合

[]#include[] []<pstade/lexical_cast.hpp>[]




[]template[][]< [][]class[] []T[][] >[]

[]void[] []foo[][]([][]T[][]& [][]x[][])[]

[]{[]

    []std[][]::[][]string[] []str[][] = [][]x[][];[]

    []BOOST_CHECK[][]( [][]str[][] == [][]"12"[][] );[]

[]}[]



[]void[] []bar[][]([][]const[] []std[][]::[][]string[][]& [][]str[][])[]

[]{[]

    []BOOST_CHECK[][]( [][]str[][] == [][]"12"[][] );[]

[]}[]



[]void[] []test[][]()[]

[]{[]

    []using[] []namespace[] []pstade[][];[]
    []std[][]::[][]string[] []str[][] = [][]pstade[][]::[][]lexical[][]([][]12[][]);[]

    []BOOST_CHECK[][]( [][]str[][] == [][]"12"[][] );[]
    []int[] []n[][] = [][]pstade[][]::[][]lexical[][]([][]str[][]);[]

    []BOOST_CHECK[][]( [][]n[][] == [][]12[][] );[]
    []BOOST_CHECK[][](([]

        []boost[][]::[][]lexical_cast[][]<[][]int[][], [][]std[][]::[][]string[][]>([]

            []pstade[][]::[][]lexical[][]([]

                []boost[][]::[][]lexical_cast[][]<[][]int[][], [][]std[][]::[][]string[][]>([]

                    []pstade[][]::[][]lexical[][]([][]12[][])[]

[]                )[]

[]            )[]

[]        ) == [][]12[]

[]    ));[]



[]    ::[][]foo[][]([][]pstade[][]::[][]lexical[][]([][]12[][]));[]

[]    ::[][]bar[][]([][]pstade[][]::[][]lexical[][]([][]12[][]));[]

[]}[]