Overloading methods by constness?

[Nathan Reed]

Hello,

In C++, you can overload methods by the constness of the method itself:

	class Foo
	{
		void bar ();		// #1
		void bar () const;	// #2
	}
	...
	Foo f;		f.bar();	// calls #1
	const Foo g;	g.bar();	// calls #2

I am wondering if there is any way to get similiar functionality in D? 
I have tried the following:

	class Foo
	{
		void bar () { ... }
		const void bar () { ... }
	}

but get a compiler error that the "bar"s conflict.

Why would I want to do this, you might ask?  Well, I would like to use 
this to write a pair of opSlice methods.  With built-in arrays, you can 
do this:

	char[] str = "Hello, world".dup;
	char[] substr = str[0..5];
	
	const(char)[] str2 = "Hello, world";
	const(char)[] substr2 = str2[0..5];
	char[] substr3 = str2[0..5]; 	// fails

i.e., the slice returns either a char[] or a const(char)[] depending on 
the constness of the array.  However, I cannot see how to make my own 
classes do the same thing, unless I can overload opSlice by constness.

Thanks,
Nathan Reed