Union Type¶
Union types refer to the ability to specify multiple possible types for a property, parameter, or return value. It allows a property or parameter to accept values of different types. It allows a method or function to return values of different types. Union types were introduced in PHP 8.
Before PHP 8, type declaration could only have a single type declaration, except for the null type. Nowadays, with union types, the code can declare multiple types by separating them with a pipe | symbol.
Union types were introduced for exception catching, before PHP 8.
<?php
class X {
private A | B | C $property;
}
try {
} catch (A|B|C $e) {
}
?>
See also What are union types and how do you use them in PHP?.
Related : Type System, Alias Types, Disjunctive Normal Form (DNF), Literal Types, Relative Types, Property Type Declaration, Intersection Type, Named Type, Type Inference
Added in PHP 8.0
