import std.stdio;

​

void main()

{

    Tester tester = new Tester(buildWriter());

    tester.run("It's OK");

}

​

struct StringWriter

{

    void put(string s)

    {

        writeln(s, ` `, a);

    }

    int a = 123;

}

​

StringWriter buildWriter()

{

    return StringWriter();

}

​

class Tester

{

    private StringWriter* writer;

​

    this(StringWriter w)

    {

        writer = &w;

        writer.put("ok");

    }

​

    void run(string m)

    {

        writer.put(m);

    }

}