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:isa

Type:   -   message selector
Source:   -   xlobj.c

Syntax

(send object :isa class) - test if object inherits from class
returns -  T  if object is an instance of class or a subclass of class, otherwise NIL

Description

The ':isa' message selector tests if an object inherits from a class.

Examples

(setq a-class (send class :new '(state)))   ; create a new class A-CLASS with STATE

(send a-class :answer :isnew '()            ; set up initialization
                             '((setq state nil) self))

(send a-class :answer :set-it '(value)      ; create :SET-IT message
                              '((setq state value)))

(setq an-obj (send a-class :new))           ; create AN-OBJ out of A-CLASS

(send an-obj :show)                         ; returns object - STATE = NIL

(send an-obj :set-it 5)                     ; STATE is set to 5
(send an-obj :show)                         ; returns object - STATE = 5

(SEND an-obj :ISNEW)                        ; re-initialize AN-OBJ
(send an-obj :show)                         ; returns object - STATE = NIL

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Nyquist / XLISP 2.0  -  Contents | Tutorials | Examples | Reference