operator new(): struct v. class

[C. Dunn]

Kirk McDonald Wrote:

> > But Walter, how did you handle operator new()?  It needs to be agnostic about class/struct.
> > 
> > class C{int x;};
> > stuct S{int x;};
> > typedef C MyType;
> > //typedef S* MyType;
> > MyType inst = new MyType;
> > 
> > If you use the second typedef, this will not compile!  That is the problem.
> > 
> > Why not provide an operator New() which expects a pointer type when used for structs?  Just have the compiler translate it.  I cannot see how to write such a generic operator New() myself.
> > 
> 
> It's a trivial bit of template code. Something like this:
> 
> T New(T)() {
> 	static if (is(T U == U*)) {
> 		return new U;
> 	} else {
> 		return new T;
> 	}
> }
> 
> class C {}
> struct S {}
> 
> void main() {
> 	C c = New!(C);
> 	S* s = New!(S*);
> }

I don't understand your static if expression.  Where in the docs is there an explanation for "is(T U == U*)"?  I completely missed that, and I really do not understand what it does.

> 
> Handling constructor arguments, too, is only a little more complicated.

Someone who can figure it out does not need to.  I think that's why people are ignoring my concern.  It's disregard for the novice.

If y'all want C++ programmers to adopt D, you have to make it easy.  C++ is entrenched.  This operator new() issue and the lack of a stack trace from an exception thrown during contract-checking weaken the arguments for adoption.  Maybe someday these will be addressed.  D certainly has potential.

And yes, before anybody mentions it, flectioned is really cool.  If it gets integrated into tango, and if tango is released for D 2.0, then the stack-trace issue might disappear.  Then maybe tango will provide an operator New().