@stdlib/array/base/accessor-getter/README.md

Arrays.

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# accessorGetter

> Return an accessor function for retrieving an element from an array-like object supporting the get/set protocol.

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## Usage

```javascript
var accessorGetter = require( '@stdlib/array/base/accessor-getter' );
```

#### accessorGetter( dtype )

Returns an accessor function for retrieving an element from an array-like object supporting the get/set protocol.

```javascript
var Complex64Array = require( '@stdlib/array/complex64' );
var realf = require( '@stdlib/complex/float32/real' );
var imagf = require( '@stdlib/complex/float32/imag' );

var arr = new Complex64Array( [ 1, 2, 3, 4 ] );

var get = accessorGetter( 'complex64' );
var v = get( arr, 1 );
// returns <Complex64>

var re = realf( v );
// returns 3.0

var im = imagf( v );
// returns 4.0
```

The returned accessor function accepts the following arguments:

-   **arr**: input array.
-   **idx**: element index.

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## Notes

-   If provided an unsupported [`dtype`][@stdlib/array/dtypes], the function returns a default accessor function for accessing elements from any indexed array-like object supporting the get/set protocol; otherwise, the function returns an accessor function which should **only** be provided an array instance corresponding to `dtype` (e.g., if `dtype` is `'complex64'`, the returned accessor function should only be provided instances of `Complex64Array`).
-   Accessor functions do **not** verify that provided input arrays are array instances corresponding to `dtype`, as doing so would introduce performance overhead. If array instances corresponding to other data types are provided to an accessor function, JavaScript runtimes will consider the function polymorphic, potentially triggering de-optimization. In order to ensure maximum performance, **always** ensure that an accessor function is monomorphic.
-   Accessor functions do **not** perform bounds checking.
-   Accessor functions do **not** verify that provided input arrays actually implement the get/set protocol.
-   An array-like object supporting the get/set protocol is a data structure in which one accesses elements using explicit `get` and `set` methods (e.g., `Complex64Array` and `Complex128Array`).

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## Examples

<!-- eslint no-undef: "error" -->

```javascript
var Complex128Array = require( '@stdlib/array/complex128' );
var Complex64Array = require( '@stdlib/array/complex64' );
var zeroTo = require( '@stdlib/array/base/zero-to' );
var dtype = require( '@stdlib/array/dtype' );
var accessorGetter = require( '@stdlib/array/base/accessor-getter' );

var arr = new Complex128Array( zeroTo( 10 ) );
var v = accessorGetter( dtype( arr ) )( arr, 2 );
// returns <Complex128>

console.log( v.toString() );
// => '4 + 5i'

arr = new Complex64Array( zeroTo( 10 ) );
v = accessorGetter( dtype( arr ) )( arr, 4 );
// returns <Complex64>

console.log( v.toString() );
// => '8 + 9i'
```

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[@stdlib/array/dtypes]: https://github.com/stdlib-js/array/tree/main/dtypes

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