Can’t use method return value in write context

Description

A write context is any position that needs an actual variable slot to write to, remove, or bind a reference to: the left side of an assignment, the target of unset(), a foreach-by-reference variable, and similar. This is the same restriction as for plain function calls, reported with a distinct message because the engine recognizes method calls (instance calls with ->, and static calls with ::) as a separate kind of AST node from ordinary function calls. A method call only produces a value; it does not designate a storage location, so it is rejected at compile time, before the method is ever invoked.

Example

<?php

class Foo {
	public function getValue() {
		return 5;
	}
}

(new Foo())->getValue() = 3;

unset((new Foo())->getValue());

?>

Alternatives

• Store the return value in a variable first, then use the variable in the write context: $v = (new Foo())->getValue(); unset($v);

Related error messages

• can’t-use-function-return-value-in-write-context
• cannot-use-result-of-built-in-function-in-write-context
• can’t-use-nullsafe-operator-in-write-context
• cannot-use-temporary-expression-in-write-context

Changed Behavior

This error may appear following an evolution in behavior, in previous versions. See