Member functions C to D

[Craig Kuhnert]

downs Wrote:

> Craig Kuhnert wrote:
> > Hi
> > I am trying to convert some code I wrote in C++ to D to give it a try and I have come across some code that I dont know how to convert.
> > I have simplified the code to illustrate the problem I have.
> > How do I do this in D?
> > 
> > class IFieldSetter
> > {
> > public:
> > 	virtual void SetValue(void * object, const void * value) = 0;
> > };
> > 
> > template <class C, class T>
> > class FieldSetter : public IFieldSetter
> > {
> > private:
> > 	typedef T (C::* MemberField);
> > 	 MemberField field;
> > 
> > public:
> > 	FieldSetter(MemberField afield)
> > 		: field(afield)
> > 	{}
> > 
> > 	void SetTypedValue(C * object, const T& value)
> > 	{
> > 		object->*field = value;
> > 	}
> > 	
> > 	void SetValue(void * object, const void * value)
> > 	{
> > 		SetTypedValue((C*) object, (const T&) value);
> > 	}
> > };
> > 
> > class MySampleClass
> > {
> > public:
> > 	int Status;
> > 	std::string Name;
> > };
> > 
> > void main(void)
> > {
> > 	IFieldSetter * StatusSetter = new FieldSetter<MySampleClass,int>(&MySampleClass::Status);
> > 	IFieldSetter * NameSetter   = new FieldSetter<MySampleClass,std::string>(&MySampleClass::Name);
> > 
> > 	MySampleClass * a = new MySampleClass();
> > 	MySampleClass * b = new MySampleClass();
> > 
> > 	StatusSetter->SetValue(a, (void*)20);
> > 	StatusSetter->SetValue(b, (void*)40);
> > 
> > 	NameSetter->SetValue(a, "2002");
> > 	NameSetter->SetValue(b, "2002");
> > }
> > 
> > Thanks
> > Craig
> 
> If I'm getting this correctly, here's one way to do it ..
> 
> module test;
> 
> import std.stdio, tools.ctfe: ctReplace; // easy to write your own ctReplace function
> 
> template Init(T) { T Init; }
> 
> interface IFieldSetter {
>   void setValue(Object obj, void* value);
> }
> 
> class FieldSetter(T: Object, string Name) : IFieldSetter {
>   override void setValue(Object obj, void* value) {
>     auto tee = cast(T) obj;
>     mixin("tee.%NAME = *cast(typeof(tee.%NAME)*) value; ".ctReplace("%NAME", Name));
>   }
>   void setValue(T obj, typeof(mixin("Init!(T)."~Name)) value) {
>     mixin("obj.%NAME = value; ".ctReplace("%NAME", Name));
>   }
> }
> 
> class Sample {
>   int status;
>   string name;
> }
> 
> void main() {
>   auto statSetter = new FieldSetter!(Sample, "status");
>   auto nameSetter = new FieldSetter!(Sample, "name");
>   auto sample = new Sample;
>   int i = 20;
>   statSetter.setValue(sample, &i);
>   statSetter.setValue(sample, 40);
>   nameSetter.setValue(sample, "Fooblr");
> }

Thanks
Thats brilliant! D rocks!
I never though of using mixin for that purpose.