import std.stdio;

import std.traits;

​

template implements(T, I)

{

    static foreach(m; __traits(allMembers, I))

    {

        static assert(

            is(typeof(__traits(getMember, T, m)) == typeof(__traits(getMember, I, m))),

            "`" ~ T.stringof ~ "` does not implement `" ~ I.stringof ~ "."

            ~__traits(identifier, __traits(getMember, I, m)) ~ "`");

    }

    enum implements = true; 

}

​

interface ISocket

{

    int send(ubyte[] data, int len);

    int recv(ubyte[] buff, int len);

}

​

struct TcpSocket

{

    int send(ubyte[] data, int len) { writeln("TcpSocket send"); return len; }

    int recv(ubyte[] buff, int len) { writeln("TcpSocket recv"); return len; }

}

​

struct UdpSocket

{

    int send(ubyte[] data, int len) { writeln("UdpSocket send"); return len; }

    int recv(ubyte[] buff, int len) { writeln("UdpSocket recv"); return len; }

}

​

struct UnixSocket

{

    int send(ubyte[] data, int len) { writeln("UnixSocket send"); return len; }

    int recv(ubyte[] buff, int len) { writeln("UnixSocket recv"); return len; }

}

​

struct NotASocket { }

​

void Use(T)(T socket) if (implements!(T, ISocket))

{

    socket.send([], 0);

    socket.recv([], 0);

}

​

void main()

{

    TcpSocket socket;

    socket.Use();   // Works out of the box without any interface boilerplate

    NotASocket noSocket;

    noSocket.Use(); // Error: no property `send`/`recv` for type `NotASocket`

}