While playing around with D 2.0 I found the following problem:

Example 1:

pure string[] run1()
{
   string[] msg;
   msg ~= "Test";
   msg ~= "this.";
   return msg;
}

This compiles and works as expected.

When I try to wrap the string array in a class I find I can not get this to work:

class TestPure
{
    string[] msg;
    void addMsg( string s )
    {
       msg ~= s;
    }
};

pure TestPure run2()
{
   TestPure t = new TestPure();
   t.addMsg("Test");
   t.addMsg("this.");
   return t;
}

This code will not compile because the addMsg function is impure. I can not make that function pure since it alters the TestPure object. Am i missing something? Or is this a limitation?

The following does compile:

pure TestPure run3()
{
    TestPure t = new TestPure();
    t.msg ~= "Test";
    t.msg ~= "this.";
    return t;
}

Would the ~= operator not been implemented as a impure function of the msg array? How come the compiler does not complain about that in the run1 function?