43 lines
1.5 KiB
Factor
43 lines
1.5 KiB
Factor
USING: classes classes.builtin classes.union.private compiler.units
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help.markup help.syntax kernel ;
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IN: classes.union
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ARTICLE: "unions" "Union classes"
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"An object is an instance of a union class if it is an instance of one of its members."
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{ $subsections
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POSTPONE: UNION:
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define-union-class
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}
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"Union classes can be introspected:"
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{ $subsections class-members }
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"The set of union classes is a class:"
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{ $subsections
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union-class
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union-class?
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}
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"Unions are used to define behavior shared between a fixed set of classes, as well as to conveniently define predicates."
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{ $see-also "mixins" "maybes" "tuple-subclassing" } ;
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ABOUT: "unions"
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HELP: (define-union-class)
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{ $values { "class" class } { "members" "a sequence of classes" } }
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{ $description "Defines a union class." }
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{ $errors "Throws " { $link cannot-reference-self } " if the definition references itself." } ;
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HELP: define-union-class
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{ $values { "class" class } { "members" "a sequence of classes" } }
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{ $description "Defines a union class with specified members. This is the run time equivalent of " { $link POSTPONE: UNION: } "." }
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{ $notes "This word must be called from inside " { $link with-compilation-unit } "." }
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{ $side-effects "class"
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} ;
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{ union-class define-union-class POSTPONE: UNION: } related-words
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HELP: union-class
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{ $class-description "The class of union classes." } ;
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HELP: union-of-builtins?
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{ $values { "class" class } { "?" boolean } }
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{ $description { $link t } " if the class either is a " { $link builtin-class } " or only contains builtin classes." } ;
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