30 lines
1.2 KiB
Factor
30 lines
1.2 KiB
Factor
USING: generic help.markup help.syntax kernel kernel.private
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namespaces sequences words arrays layouts help effects math
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layouts classes.private classes compiler.units ;
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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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{ $subsection POSTPONE: UNION: }
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{ $subsection define-union-class }
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"Union classes can be introspected:"
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{ $subsection members }
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"The set of union classes is a class:"
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{ $subsection union-class }
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{ $subsection union-class? }
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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" "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 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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{ 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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