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# accessorSetter

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

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## Usage

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

#### accessorSetter( dtype )

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

```javascript
var Complex64Array = require( '@stdlib/array/complex64' );
var Complex64 = require( '@stdlib/complex/float32/ctor' );
var realf = require( '@stdlib/complex/float32/real' );
var imagf = require( '@stdlib/complex/float32/imag' );

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

var set = accessorSetter( 'complex64' );
set( arr, 1, new Complex64( 10.0, 11.0 ) );

var v = arr.get( 1 );
// returns <Complex64>

var re = realf( v );
// returns 10.0

var im = imagf( v );
// returns 11.0
```

The returned accessor function accepts the following arguments:

-   **arr**: input array.
-   **idx**: element index.
-   **value**: value to set.

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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** validate input values.
-   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 Complex128 = require( '@stdlib/complex/float64/ctor' );
var Complex64 = require( '@stdlib/complex/float32/ctor' );
var zeroTo = require( '@stdlib/array/base/zero-to' );
var dtype = require( '@stdlib/array/dtype' );
var accessorSetter = require( '@stdlib/array/base/accessor-setter' );

var arr = new Complex128Array( zeroTo( 10 ) );
accessorSetter( dtype( arr ) )( arr, 2, new Complex128( 100.0, 101.0 ) );

var v = arr.get( 2 );
// returns <Complex128>

console.log( '%s', v.toString() );
// => '100 + 101i'

arr = new Complex64Array( zeroTo( 10 ) );
accessorSetter( dtype( arr ) )( arr, 4, new Complex64( 102.0, 103.0 ) );

v = arr.get( 4 );
// returns <Complex64>

console.log( '%s', v.toString() );
// => '102 + 103i'
```

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

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