The above described procedures should be sufficient for most needs. This module does, however, provide a few procedures to allow programmers to access type definitions. These may be a convenience for debugging, or in writing tools to manipulate type definitions.
The following procedures allow programmers to find the definition of a given type:
type_definition(+Type, -Definition) type_definition(*Type, *Definition) type_definition(+Type, -Definition, -Size) type_definition(*Type, *Definition, *Size)
Type is an atom naming a type, Definition is the definition of that
type, and Size is the number of bytes occupied by a foreign term of
this type. Size will be the atom
unknown if the size of an object of
that type is not known. Such types may not be used as fields in
structs or unions, or in arrays. However, pointers to them may be
created. If Type is not bound at call time, these procedures will
backtrack through all current type definitions.
A definition looks much like the definition given when the type was
type/1, except that it has been simplified. Firstly,
intermediate type names have been elided. For example, if
type_definition(bar, integer) would hold. Also, in the definition
of a compound type, types of parts are always defined by type names,
rather than complex specifications. So if the type of a field in a
struct was defined as
pointer(fred), it will show up in the
'$fred'. Of course,
type_definition('$fred', pointer(fred)) would hold, also.
The following predicates allow the programmer to determine whether or not a given type is atomic:
atomic_type(+Type) atomic_type(*Type) atomic_type(+Type, -Primitive_type) atomic_type(*Type, *Primitive_type) atomic_type(+Type, -Primitive_type, -Size) atomic_type(*Type, *Primitive_type, *Size)
Type is an atomic type. See str-fty for the definition
of an atomic type. Primitive_type is the primitive type that
Type is defined in terms of. Size is the number of bytes
occupied by an object of type Type, or the atom
above. If Type is unbound at call time, these predicates will
backtrack through all the currently defined atomic types.