feat: add custom valueOf method

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---

Author: kgryte

lib/node_modules/@stdlib/ndarray/dtype-ctor/README.md

@@ -194,6 +194,20 @@ var str = dt.toString();
 // returns 'float64'
 ```
 
+#### DataType.prototype.valueOf()
+
+Converts a `DataType` instance to a primitive value.
+
+```javascript
+var dt = new DataType( 'float64' );
+// returns <DataType>
+
+var str = dt.valueOf();
+// returns 'float64'
+```
+
+This method returns the same value as `#.toString()`.
+
 </section>
 
 <!-- /.usage -->

lib/node_modules/@stdlib/ndarray/dtype-ctor/benchmark/benchmark.js

@@ -314,3 +314,29 @@ bench( pkg+':toString', function benchmark( b ) {
 	b.pass( 'benchmark finished' );
 	b.end();
 });
+
+bench( pkg+':valueOf', function benchmark( b ) {
+	var values;
+	var v;
+	var i;
+
+	values = [
+		new DataType( 'float64' ),
+		new DataType( 'float32' ),
+		new DataType( 'generic' )
+	];
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		v = values[ i%values.length ].valueOf();
+		if ( typeof v !== 'string' ) {
+			b.fail( 'should return a string' );
+		}
+	}
+	b.toc();
+	if ( typeof v !== 'string' ) {
+		b.fail( 'should return a string' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});

lib/node_modules/@stdlib/ndarray/dtype-ctor/docs/repl.txt

@@ -192,6 +192,23 @@
     > dt.toString()
     'float64'
 
+
+{{alias}}.prototype.valueOf()
+    Converts a data type instance to a primitive.
+
+    This method returns the same value as `#.toString()`.
+
+    Returns
+    -------
+    out: string
+        Primitive value.
+
+    Examples
+    --------
+    > var dt = new {{alias}}( 'float64' );
+    > dt.valueOf()
+    'float64'
+
     See Also
     --------
 

lib/node_modules/@stdlib/ndarray/dtype-ctor/docs/types/index.d.ts

@@ -199,6 +199,24 @@ declare class DataType<T = unknown> {
 	* // returns 'float64'
 	*/
 	toString(): string;
+
+	/**
+	* Converts a data type instance to a primitive value.
+	*
+	* ## Notes
+	*
+	* -   This method returns the same value as `#.toString()`.
+	*
+	* @returns primitive value
+	*
+	* @example
+	* var dt = new DataType( 'float64' );
+	* // returns <DataType>
+	*
+	* var v = dt.valueOf();
+	* // returns 'float64'
+	*/
+	valueOf(): string;
 }
 
 

lib/node_modules/@stdlib/ndarray/dtype-ctor/docs/types/test.ts

@@ -62,6 +62,13 @@ import DataType = require( './index' );
 	x.toJSON(); // $ExpectType Object
 }
 
+// Attached to a data type instance is a `valueOf` method which returns a string...
+{
+	const x = new DataType( 'float64' ); // $ExpectType DataType<string>
+
+	x.valueOf(); // $ExpectType string
+}
+
 // The compiler throws an error if the constructor is provided an unsupported number of arguments...
 {
 	new DataType(); // $ExpectError

lib/node_modules/@stdlib/ndarray/dtype-ctor/lib/main.js

@@ -350,6 +350,25 @@ setReadOnly( DataType.prototype, 'toString', function toString() {
 	return ( this._type === 'struct' ) ? this._value.layout : String( this._value );
 });
 
+/**
+* Converts a data type instance to a primitive value.
+*
+* @name valueOf
+* @memberof DataType.prototype
+* @type {Function}
+* @returns {string} primitive value
+*
+* @example
+* var dt = new DataType( 'float64' );
+* // returns <DataType>
+*
+* var v = dt.valueOf();
+* // returns 'float64'
+*/
+setReadOnly( DataType.prototype, 'valueOf', function valueOf() {
+	return this.toString();
+});
+
 
 // EXPORTS //
 

lib/node_modules/@stdlib/ndarray/dtype-ctor/test/test.js

@@ -341,3 +341,15 @@ tape( 'the constructor returns an instance which supports serializing an instanc
 
 	t.end();
 });
+
+tape( 'the constructor returns an instance which supports converting an instance to a primitive value', function test( t ) {
+	var dt;
+
+	dt = new DataType( 'float64' );
+	t.strictEqual( dt.valueOf(), 'float64', 'returns expected value' );
+
+	dt = new DataType( 'float32' );
+	t.strictEqual( dt.valueOf(), 'float32', 'returns expected value' );
+
+	t.end();
+});