Page 213 Table of Contents Index Page 215
Chapters
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30
A, B, C, D, E



CHAPTER 23. PRESENTATION TYPES

Implementation note: the actual argument list to the presentation-type-specifier-p
method is
(type-key parameters options type)

=> presentation-typep object type [Presentation Method]
The presentation-typep method is called when the presentation-typep function requires
type-specific knowledge. If the type name in the presentation type type is a CLOS class or
names a CLOS class, the method is called only if object is a member of the class and type
contains parameters, and the method simply tests whether object is a member of the subtype
specified by the parameters. For non-class types, the method is always called.

Implementation note: the actual argument list to the presentation-typep method is
(type-key parameters object type)

=> presentation-subtypep type putative-supertype [Presentation Method]
presentation-subtypep walks the type lattice (using map-over-presentation-supertypes)
to determine whethe or not the presentation type type is a subtype of thepresentation type
putative-supertype, without looking at the type parameters. When a supertype of type has been
found whose name is the same as the name of putative-supertype, then the subtypep method for
that type is called in order to resolve the question by looking at the type parameters (that is, if
the subtypep method is called, type and putative-supertype are guaranteed to be the same type,
differing only in their parameters). If putative-supertype is never found during the type walk,
then presentation-subtypep will never call the presentation-subtypep presentation method
for putative-supertype.

Unlike all other presentation methods, presentation-subtypep receives a type argument that
has been translated to the presentation type for which the method is specialized; type is never a
subtype. The method is only called if putative-supertype has parameters and the two presentation
type specifiers do not have equal parameters. The method must return the two values that
presentation-subtypep returns.

Since presentation-subtypep takes two type arguments, the parameters are not lexically avail-
able as variables in the body of a presentation method.

Implementation note: the actual argument list to the presentation-subtypep method is
(type-key type putative-supertype)

=> map-over-presentation-type-supertypes function type [Presentation Method]
This method is called in order to apply function to the superclasses of the presentation type
type.

Implementation note: the actual argument list to the map-over-presentation-type-supertypes
method is
(type-class function type)

=> accept-present-default type stream view default default-supplied-p present-p query-identifier
[Presentation Method]


Page 213 Table of Contents Index Page 215
Chapters
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30
A, B, C, D, E