Singleton types

Singleton types

Singleton types are those which allow only one value. PHP has support for two singleton types: as of PHP 8.0.0 and as of PHP 8.2.0. false``true

Waarschuwing: > Prior to PHP 8.2.0 the type could only be used as part of a . falseunion type

Opmerking: > It is not possible to define custom singleton types. Consider using an instead. enumerations