enum i(string expr) =

    "new class(" ~ expr ~ ") {\n" ~ 

    "    alias _T = typeof(" ~ expr ~ ");\n" ~

    "    _T _v;\n" ~

    "        this(_T _v) {\n" ~

    "            this._v = _v;\n" ~

    "    }\n" ~

    "    static if (is(_T : int)) {\n" ~

    "        enum formatString =  \"%s (detected integer): %d\";\n" ~

    "    } else static if (is(_T : double)) {\n" ~

    "        enum formatString = \"%s (detected double): %f\";\n" ~

    "    } else {\n" ~

    "        enum formatString = \"%s (default: \" ~ _T.stringof ~ \"): %s\";\n" ~

    "    }\n" ~

    "    alias _seq =  imported!\"std.meta\".AliasSeq!(formatString,\"" ~ expr ~ "\",_v);\n " ~

    "}._seq";

​

void main() {

    import std.stdio : writefln;

    import std.math : sqrt;

​

    int a = 5;

​

    writefln(mixin(i!"a + 10"));

    // a + 10 (detected integer): 15

    writefln(mixin(i!"sqrt(5.0) / 2"));

    // sqrt(5.0) / 2 (detected double): 1.118034

    string b = "5";

    writefln(mixin(i!"b"));

    // b (default: string): 5

}

​