NullObject

Factory and detector for null object instances.

Import

import { NullObject, ValueObject } from '@haskou/value-objects';

Signature

abstract class NullObject

Constructor

Not constructed directly.

Automatic creation

Automatic NullObject creation is enabled by default. Constructing a ValueObject with null or undefined returns a compatible null object.

Applications that prefer immediate failure can disable that behavior globally:

ValueObject.disableNullObjectCreation();

With automatic creation disabled, nullish construction throws NullObjectCreationDisabledError. Restore the default behavior with ValueObject.enableNullObjectCreation().

The setting is process-wide and should normally be configured once during application bootstrap.

Validation

NullObject.new() creates an object with isNullObject: true, valueOf(): undefined, and fake methods that throw NullObjectError.

Methods

Method	Description
static new(klass)	Creates a null object compatible with the requested class.
static isNullObject(value)	Returns true when the value looks like a null object.

Example

import { NullObject, StringValueObject } from '@haskou/value-objects';

const value = new StringValueObject(undefined as never);

NullObject.isNullObject(value); // true
value.valueOf(); // undefined

Notes

• Calling most class methods on a null object throws NullObjectError.
• ValueObject.disableNullObjectCreation() does not remove NullObject.new(); explicit null objects remain available.

Related

• Null objects guide
• ValueObject
• Error handling
• Reference overview