"The class of all objects. If a generic word defines a method specializing on this class, the method is used as a fallback, if no other applicable method is found. For instance:"
{ $values { "class" "a class word" } { "predicate" "a predicate word" } { "quot" "a quotation" } }
{ $description
"Defines a predicate word. This is identical to a compound definition associating " { $snippet "quot" } " with " { $snippet "predicate" } " with the added perk that two word properties are set:"
{ $list
{ "the class word's " { $snippet "\"predicate\"" } " property is set to a quotation that calls the predicate" }
{ "the predicate word's " { $snippet "\"predicating\"" } " property is set to the class word" }
}
"These properties allow the method combination code to generate method dispatch logic."
{ $values { "class" "a class word" } { "super" "a class word" } }
{ $description "Outputs the superclass of a class. All instances of this class are also instances of the superclass." }
{ $notes "If " { $link class< } " yields that one class is a subtype of another, it does not imply that a superclass relation is involved. The superclass relation is a technical implementation detail of predicate classes (see " { $link POSTPONE: PREDICATE: } ").." } ;
HELP: members "( class -- seq )"
{ $values { "class" "a class word" } { "seq" "a sequence of union members, or " { $link f } } }
{ $description "If " { $snippet "class" } " is a union class, outputs a sequence of members, otherwise outputs " { $link f } "." } ;
{ $values { "class" "a class word" } { "seq" "a sequence of classes" } }
{ $description "Outputs a sequence of classes whose union is the given class. Unless the given class is a union class, the output is just a singleton sequence consisting of the given class." } ;
{ $description "Constructs a hashtable mapping classes to hashtables of classes which are smaller than them under " { $link class< } "." }
{ $notes "This word should not be called directly. Instead, use " { $link with-class<cache } "." } ;
HELP: with-class<cache
{ $values { "quot" "a quotation" } }
{ $description "Calls the quotation in a new dynamic scope where the " { $link class<cache } " variable is bound to a hashtable output by " { $link make-class<cache } ". When this variable is bound, " { $link class< } " can be performed much more quickly than usual." }
{ $notes "Calls to compile large numbers of words can be wrapped in this combinator to reduce compile time." } ;
{ $values { "classes" "a hashtable mapping class words to themselves" } { "class" "a class word" } }
{ $description "Given a set of classes represented as a hashtable with equal keys and values, looks up a previously-defined union class having those members. If no union is defined, outputs " { $link object } "." }
{ $values { "class1" "a class word" } { "class2" "a class word" } { "class" "a class word" } }
{ $description "Outputs a class whose instances are instances of either one of the two input classes. If the union is non-empty but no class with those members is defined, outputs " { $link object } "." } ;
{ $values { "class1" "a class word" } { "class2" "a class word" } { "class" "a class word" } }
{ $description "Outputs a class whose instances are instances of both input classes. If the intersection is non-empty but no class with those members is defined, outputs " { $link object } ". If the intersection is empty, outputs " { $link null } "." } ;
{ $values { "class" "a class word" } { "seq" "a sequence of class words" } { "class/f" "a class word or " { $link f } } }
{ $description "If all classes in " { $snippet "seq" } " that intersect " { $snippet "class" } " are subtypes of " { $snippet "class" } ", outputs the last such element of " { $snippet "seq" } ". If any conditions fail to hold, outputs " { $link f } "." } ;
