built-in types (the first was in revision 21877). When an exception
has raised within from the __init__ method of a user-defined class
derived from a built-in type (e.g., UnaryPredicate0D and
BinaryPredicate1D), some member variables of the base type are
left uninitialized, leading to a null pointer reference in the
"__dealloc__" function in the base type. To avoid this, pointer
checking was added in the deallocators of those built-in types that
can be used to define a subclass by a user.
callable(I, T) returns True when I is an object of a type T or
of a subtype of T. Also implemented a measure to avoid an
infinite loop when user-defined predicate and function classes
do not properly overload the __call__ method (including the
cases of directly instantiating the base classes such as
UnaryPredicate0D and BinaryPredicate1D).
