Hiding class pointers -- was it a good idea?

[eao197]

On Thu, 16 Aug 2007 12:28:07 +0400, Bill Baxter  
<dnewsgroup at billbaxter.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.

I suppose that the problem becomes more complex in the case when template  
class has some methods which receive or return objects by reference or by  
value. In C++ it is straightforward, but in D it is required some  
static-if-metaprogramming.

-- 
Regards,
Yauheni Akhotnikau