Здравствуйте, _DAle_, Вы писали:

_DA>

The declaration of a static data member in its class definition is not a definition and may be of an incomplete type other than cv-qualified void. The definition for a static data member shall appear in a namespace scope enclosing the member’s class definition. In the definition at namespace scope, the name of the static data member shall be qualified by its class name using the :: operator.

Понял. Спасибо.
Жаль. Было бы красиво.