Need help to compile code with traits

[Xavier Bigand via Digitalmars-d-learn]

Hi,

I am trying to create an allocator that don't use the GC, and I have 
issues for the initialization of member before calling the constructor.
Here is my actual code :
mixin template NogcAllocator(T)
{
        static T        nogcNew(T, Args...)(Args args) @nogc
        {
                import core.stdc.stdlib : malloc;
                import std.traits;
                T       instance;

                instance = cast(T)malloc(__traits(classInstanceSize, T));
                foreach (string member; __traits(allMembers, T))
                {
                        static if (isType!(__traits(getMember, T, member)))
                                __traits(getMember, instance, member) = 
typeof(__traits(getMember, T, member)).init;
                }

                instance.__ctor(args);
                return instance;
        }

        static void     nogcDelete(T)(T instance) @nogc
        {
                import core.stdc.stdlib : free;

                instance.__dtor();
                free(instance);
        }
}

unittest
{
        struct Dummy {
                int field1 = 10;
                int field2 = 11;
        }

        class MyClass {
                mixin NogcAllocator!MyClass;

                int a = 0;
                int[] b = [1, 2, 3];
                Dummy c = Dummy(4, 5);

                int d = 6;

                this() @nogc {
                }

                this(int val) @nogc {
                        d = val;
                }
        }

        MyClass first = MyClass.nogcNew!MyClass();
        MyClass second = MyClass.nogcNew!MyClass(7);

        assert(first.a == 0);
        assert(first.b == [1, 2, 3]);
        assert(first.c.field1 == 4);
        assert(first.d == 6);

        assert(second.c.field1 == 4);
        assert(second.d == 7);
}


And the compilation errors :
..\src\core\nogc_memory.d(16): Error: no property 'this' for type 
'core.nogc_memory.__unittestL39_3.MyClass'
..\src\core\nogc_memory.d(17): Error: type Monitor is not an expression
..\src\core\nogc_memory.d(63): Error: template instance 
core.nogc_memory.__unittestL39_3.MyClass.NogcAllocator!(MyClass).nogcNew!(MyClass)
 error instantiating
..\src\core\nogc_memory.d(16): Error: no property 'this' for type 
'core.nogc_memory.__unittestL39_3.MyClass'
..\src\core\nogc_memory.d(17): Error: type Monitor is not an expression
..\src\core\nogc_memory.d(64): Error: template instance 
core.nogc_memory.__unittestL39_3.MyClass.NogcAllocator!(MyClass).nogcNew!(MyClass,
 int) error instantiating

I don't understand my mistake with the getMember and isType traits.
And I am curious about of what is the Monitor.