111 lines
2.3 KiB
Markdown
111 lines
2.3 KiB
Markdown
<!--
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@license Apache-2.0
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Copyright (c) 2019 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# Memoized Read-Only
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> [Define][mdn-define-property] a memoized **read-only** object property.
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<section class="usage">
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## Usage
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```javascript
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var setMemoizedReadOnly = require( '@stdlib/utils/define-memoized-read-only-property' );
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```
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#### setMemoizedReadOnly( obj, prop, fcn )
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[Defines][mdn-define-property] a memoized **read-only** object property.
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```javascript
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var obj = {};
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function foo() {
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return 'bar';
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}
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setMemoizedReadOnly( obj, 'foo', foo );
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var v = obj.foo;
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// returns 'bar'
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```
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The last argument should be a synchronous function whose return value will be memoized and set as the property value.
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</section>
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<!-- /.usage -->
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<section class="notes">
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## Notes
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- A **read-only** property is **enumerable** and **non-configurable**; however, until deferred evaluation, an object property is **configurable**.
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</section>
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<!-- /.notes -->
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<section class="examples">
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## Examples
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<!-- eslint no-undef: "error" -->
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```javascript
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var fibonacci = require( '@stdlib/math/base/special/fibonacci' );
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var setMemoizedReadOnly = require( '@stdlib/utils/define-memoized-read-only-property' );
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function Foo() {
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var self;
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if ( !(this instanceof Foo) ) {
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return new Foo();
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}
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self = this;
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this.count = 0;
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setMemoizedReadOnly( this, 'fibo', fibo );
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return this;
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function fibo() {
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self.count += 1;
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return fibonacci( 73 );
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}
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}
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var foo = new Foo();
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var i;
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for ( i = 0; i < 10; i++ ) {
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console.log( 'F: %d. Count: %d.', foo.fibo, foo.count );
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}
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```
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</section>
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<!-- /.examples -->
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<section class="links">
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[mdn-define-property]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/defineProperty
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</section>
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<!-- /.links -->
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