Forward declaration of legacy bdef_Function in order to implement by-reference conversion from bsl::function<F>. This declaration produces a by-name cyclic dependency between bsl and bde in order to allow legacy code to transition to bsl::function from (the deprecated) bdef_Function. The conversion, and therefore this forward reference, should not appear in the open-source version of this component.
Declared in <bslstl_function.h>
template<class PROTOTYPE>
class bdef_Function;