Table of Contents

PHP RFC: Deprecate returning values from __construct() and __destruct()

Introduction

A class’ constructor and destructor (“Lifecycle Functions”) are special in that they are not meant to be used like regular methods and called manually. Observing the return value during intended use is not possible.

To that effect they are already restricted from declaring any return type at all, including declaring a return type of void. It however is nevertheless legal to return a value from these methods, which can be confusing, particularly when returning a separate valid object instance from __construct().

Proposal

Deprecate returning values from __construct() and __destruct(). Using return …; shall emit a compile-time deprecation. Using return; without an expression to “skip” over the remaining logic shall remain legal. Starting with the next major version, returning a value shall emit a compile-time error. 

<?php
 
class Foo
{
	public function __construct()
	{
		return 123; // Deprecated: Returning a value from a constructor is deprecated in test.php on line 6
	}
 
	public function __destruct()
	{
		return 123; // Deprecated: Returning a value from a constructor is deprecated in test.php on line 11
	}
}
 
class Bar
{
	public function __construct()
	{
		if (random_int(0, 1)) {
			return; // Skipping the rest of the logic remains legal.
		}
 
		echo "Constructing", PHP_EOL;
	}
}

This deprecation is in line with the existing error when returning a value from a void function: 

<?php
 
function void_function(): void
{
	return 123; // Fatal error: A void function must not return a value in test.php on line 5
}

It will remain legal to manually call __construct() and __destruct(), for example to call a parent constructor or destructor - or to initialize a lazy object.

Backward Incompatible Changes

The deprecation itself is not a backwards incompatible change. When it is turned into an error, code that returns values will stop working. The justification is provided in the introduction.

Proposed PHP Version(s)

Deprecation in the next PHP version (8.6). Removal in the first major after that.

RFC Impact

To the Ecosystem

Static analyzers and IDEs will want to point out:

To Existing Extensions

None.

To SAPIs

None.

Open Issues

None.

Future Scope

Similar arguments apply to __clone(). However in that case specifying an explicit return type of void is legal. __clone() will therefore implicitly be handled if / when magic methods are required to specify accurate return (and parameter) types.

Voting Choices

Primary Vote requiring a 2/3 majority to accept the RFC:

Deprecate returning values from __construct() and __destruct()?
Real name Yes No Abstain
Final result: 0 0 0
This poll has been closed.

Patches and Tests

https://github.com/php/php-src/pull/21982

Implementation

After the RFC is implemented, this section should contain:

  1. the version(s) it was merged into
  2. a link to the git commit(s)
  3. a link to the PHP manual entry for the feature

References

Rejected Features

None.

Changelog