Hiding class pointers -- was it a good idea?

[Bill Baxter]

eao197 wrote:
> On Thu, 16 Aug 2007 01:35:17 +0400, Walter Bright 
> <newshound1 at digitalmars.com> wrote:
> 

>> 3) Value types just don't work for polymorphic behavior. They must be 
>> by reference. There's no way in C++ to ensure that your class 
>> instances are used properly by reference only (hence (2)). In fact, in 
>> C++, it's *extra work* to use them properly.
> 
> But from another side all types in C++ (internal or user defined) is a 
> first class citizens. It is especially important in generic programming, 
> where I can write:
> 
> template< class T >
> class ValueHolder {
>   T * m_value
> public :
>   ValueHolder() : m_value( new T() ) {}
>   ...
> };
> 
> and this code will work as with int, as with std::string, as with 
> ValueHolder<SomeAnotherType>.

I hear you.  Fortunately it's pretty trivial to throw some 
static-if-is-zzle at the problem in D.  May not be so pretty, but it's 
straightforward at least.

--bb