From the standard section 9.4.2: If a static data member is of const integral or const enumeration type, its declaration in the class definition can specify a constant-initializer which shall be an integral constant expression. In that case, the member can appear in integral constant expressions within its scope. The member shall still be defined … Read more
This is core issue 728, which was filed before generic lambdas were a thing. You mentioned generic lambdas and that they were identical to local classes with corresponding member template operator(). However, they actually aren’t, and the differences are related to implementation characteristics. Consider template <typename T> class X { template <typename> void foo() { … Read more
The purpose of this limitation? Just a guess, but: you may use the template class/template member function only within the enclosing function. Therefore you already know all used types within the function and hence can directly specify the used types (for several types, of course, the template variant would have saved some typing). although it … Read more
To me this seems to be an oversight or limitation in the Java language and I do not think it is possible. The referenced type in an instanceof expression must be reifiable according to JLS 4.7, meaning that it must be expressed as a reifiable type by its fully qualified name. At the same time, … Read more
This is called a local class. 2 is the easy one: yes, a class file will be generated. 1 and 3 are kind of the same question. You would use a local class where you never need to instantiate one or know about implementation details anywhere but in one method. A typical use would be … Read more