This is an idea that has been roaming around my head for some 20 years!

 

As we know, there is a list of some 15 (or so) operations (construction,
assignment, copy, move, conversion, etc.) that the simple statement: "class
T {};" defines.

 

If one wishes some control over this behavior, one has to be knowledgeable
in all that the compiler provides. In non-C++ terms, one has to say (modern
use: =delete), "I don't want that, I don't want this, etc." The compiler
provides no aid for this!

 

My notion is to reverse this via "explicit class T {};". While I am sure
there are some details that would need to be debated, this would eliminate
(most) everything that the compiler defines for you. Thus, if you wanted
something, you would have to define it or use " = default" (yes, I am aware
that would require extending "= default" to more items - seems OK to me).
The obvious advantage is that the compiler now provides some help, in that
using something that is not defined will yield a compiler error.

 

Does anyone know if this has been proposed before? If not, what do you
think?

 

Thanks in advance!