Define Memoized Property

Define a memoized object property.

Usage

var defineMemoizedProperty = require( '@stdlib/utils/define-memoized-property' );

defineMemoizedProperty( obj, prop, descriptor )

Defines a memoized object property.

var obj = {};

function foo() {
    return 'bar';
}

defineMemoizedProperty( obj, 'foo', {
    'configurable': false,
    'enumerable': true,
    'writable': false,
    'value': foo
});

var v = obj.foo;
// returns 'bar'

A property descriptor has the following required properties:

  • value: synchronous function whose return value will be memoized and set as the property value.

A property descriptor has the following optional properties:

  • configurable: boolean indicating if property descriptor can be changed and if the property can be deleted from the provided object. Default: false.
  • enumerable: boolean indicating if the property shows up when enumerating object properties. Default: false.
  • writable: boolean indicating if the value associated with the property can be changed with an assignment operator. Default: false.

Notes

  • Until deferred evaluation, an object property is configurable.

Examples

var fibonacci = require( '@stdlib/math/base/special/fibonacci' );
var defineMemoizedProperty = require( '@stdlib/utils/define-memoized-property' );

function Foo() {
    var self;
    if ( !(this instanceof Foo) ) {
        return new Foo();
    }
    self = this;
    this.count = 0;
    defineMemoizedProperty( this, 'fibo', {
        'value': fibo
    });
    return this;

    function fibo() {
        self.count += 1;
        return fibonacci( 73 );
    }
}

var foo = new Foo();

var i;
for ( i = 0; i < 10; i++ ) {
    console.log( 'F: %d. Count: %d.', foo.fibo, foo.count );
}