PHP RFC: instanceof improvements

• Version: 1.0
• Date: 2020-05-17
• Author: Max Semenik, maxsem.wiki@gmail.com
• Status: Draft
• First Published at: http://wiki.php.net/rfc/instanceof_improvements

As currently implemented, the `instanceof` operator is inconsistent.

var_dump(new MyClass instanceof MyClass); // true

So far so good? What if we tried to use a scalar type? They can be specified as parameter types just like class names, right?

$x = 123;
var_dump($x instanceof int); // false, right hand side is always treated as a class name

Make instanceof support non-object types:

var_dump('foo' instanceof string)       // true
var_dump('foo' instanceof ('string'))   // true
$type = 'string';
var_dump('foo' instanceof $type);       // true

What breaks, and what is the justification for it?

PHP 8.1.

Describe the impact to CLI, Development web server, embedded PHP etc.

Will existing extensions be affected?

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Describe any new constants so they can be accurately and comprehensively explained in the PHP documentation.

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This section details areas where the feature might be improved in future, but that are not currently proposed in this RFC.

What should be done about this (improve instanceof / add new operator / reject this RFC)?

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