factor/examples/oop.factor

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Factor

! :sidekick.parser=none:
IN: oop
USE: combinators
USE: errors
USE: hashtables
USE: kernel
USE: lists
USE: namespaces
USE: parser
USE: stack
USE: strings
USE: words
SYMBOL: traits
: traits-map ( type -- hash )
#! The method map word property maps selector words to
#! definitions.
"traits-map" word-property ;
: object-map ( obj -- hash )
dup has-namespace? [ traits swap get* ] [ drop f ] ifte ;
: init-traits-map ( word -- )
<namespace> "traits-map" set-word-property ;
: no-method
"No applicable method." throw ;
: method ( traits selector -- quot )
#! Execute the method with the traits object on the stack.
over object-map hash* [ cdr ] [ [ no-method ] ] ifte* ;
: constructor-word ( word -- word )
word-name "<" swap ">" cat3 "in" get create ;
: define-constructor ( word -- )
#! <foo> where foo is a traits type creates a new instance
#! of foo.
[ constructor-word [ <namespace> ] ] keep
traits-map [ traits pick set* ] cons append
define-compound ;
: predicate-word ( word -- word )
word-name "?" cat2 "in" get create ;
: define-predicate ( word -- )
#! foo? where foo is a traits type tests if the top of stack
#! is of this type.
dup predicate-word swap
[ object-map ] swap traits-map [ eq? ] cons append
define-compound ;
: TRAITS:
#! TRAITS: foo creates a new traits type. Instances can be
#! created with <foo>, and tested with foo?.
CREATE
dup define-symbol
dup init-traits-map
dup define-constructor
define-predicate ; parsing
: GENERIC:
#! GENERIC: bar creates a generic word bar that calls the
#! bar method on the traits object, with the traits object
#! on the stack.
CREATE
dup unit [ car method call ] cons
define-compound ; parsing
: M: ( -- type generic [ ] )
#! M: foo bar begins a definition of the bar generic word
#! specialized to the foo type.
scan-word scan-word f ; parsing
: ;M ( type generic def -- )
#! ;M ends a method definition.
rot traits-map [ reverse put ] bind ; parsing