28 lines
580 B
Racket
28 lines
580 B
Racket
#lang scribble/manual
|
|
@(require (for-label racket))
|
|
|
|
@title{RefCopy}
|
|
a reference to the copy of a value@section{categories}
|
|
Core
|
|
|
|
@section{description}
|
|
|
|
A Ref instance is an object with a single slot named 'value' that serves as a holder of an object.
|
|
RefCopy, in difference to Ref, returns only copies of the value when next is called.
|
|
This can be useful when the original is to be kept unchanged.
|
|
|
|
see link::Classes/Ref:: for other methods.
|
|
|
|
@section{examples}
|
|
|
|
|
|
|
|
@racketblock[
|
|
a = [1, 2, 3];
|
|
x = RefCopy(a);
|
|
b = x.next;
|
|
b.put(0, 100); // modify b
|
|
a; // a is unchanged.
|
|
]
|
|
|
|
|