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PHPDoc Types

A PHPDoc type is what’s written in place of [Type] in annotations like @var [Type] or @param [Type] $foo.

Basic types #

• int, integer
• positive-int, negative-int
• string
• bool, boolean
• true
• false
• null
• float
• double
• array
• iterable
• callable
• resource
• void
• object

Mixed #

mixed type can be used if we don’t want to define a more specific type. PHPStan doesn’t check anything on the mixed type - any property or method can be called on it and it can be passed to any type in a function/method call.

PHPStan has a concept of implicit and explicit mixed. Missing typehint is implicit mixed - no type was specified as a parameter type or a return type. Explicit mixed is written in the PHPDoc. PHPStan’s rule level 6 isn’t satisfied with implicit mixed, but an explicit one is sufficient.

Classes and interfaces #

A fully-qualified name (FQN) like \Foo\Bar\Baz, or a relative name like Baz resolved based on the current namespace and use statements can be used.

Trait names cannot be used in PHPDocs, as they don’t work as native PHP typehints either.

General arrays #

• Type[]
• array<Type>
• array<int, Type>
• non-empty-array<Type>
• non-empty-array<int, Type>

Iterables #

• iterable<Type>
• Collection<Type>
• Collection<int, Type>
• Collection|Type[]

These notations specify the iterable key and value types in a foreach statement.

These iterable rules are applied only when the Collection type isn’t generic. When it’s generic, generics rules for class-level type variables are applied.

If PHP encounters Collection|Foo[], two possible paths are taken:

1. Collection implements Traversable so Collection|Foo[] is interpreted as a Collection object that iterates over Foo. The array part isn’t applied.
2. Collection does not implement Traversable so Collection|Foo[] is interpreted as a Collection object or an array of Foo objects.

If Collection|Foo[] means "Collection or array" in your case even if Collection implements Traversable, you need to disambiguate the type by using Collection|array<Foo> instead.

Union types #

Written as Type1|Type2. Read more about union types here »

Intersection types #

Written as Type1&Type2. Read more about intersection types here »

Parentheses #

Parentheses can be used to disambiguate types: (Type1&Type2)|Type3

static and $this #

To denote that a method returns the same type it’s called on, use @return static or @return $this.

This is useful if we want to tell that a method from a parent class will return an object of the child class when the parent class is extended (see example).

A narrower @return $this instead of @return static can also be used, and PHPStan will check if you’re really returning the same object instance and not just an object of the child class.

Generics #

Generics »

class-string #

class-string type can be used wherever a valid class name string is expected. Generic variant class-string<T> also works.

/**
 * @param class-string $className
 */
function foo(string $className): void { ... }

Both literal strings with valid class names ('stdClass') and class constants (\stdClass::class) are accepted as class-string arguments.

If you have a general string and want to pass it as a class-string argument, you need to make sure the string contains a valid class name:

function bar(string $name): void
{
    if (class_exists($name)) { // or interface_exists()
        // $name is class-string here
        foo($name);
    }
}

Other advanced string types #

There’s also callable-string and numeric-string.

Type aliases #

Type aliases (also known as typedef) are a popular feature in other languages like TypeScript or C++. Using the following configuration in the configuration file will allow you to reference these types in your PHPDocs:

parameters:
	typeAliases:
		Name: 'string'
		NameResolver: 'callable(): string'
		NameOrResolver: 'Name|NameResolver'

Your code can look like this:

/**
 * @param NameOrResolver $arg
 */
function foo($arg)
{
	// $arg is string|(callable(): string)
}

Array shapes #

This feature enables usage of strong types in codebases where arrays of various specific shapes are passed around functions and methods. PHPStan checks that the values in specified keys have the correct types:

• array{'foo': int, "bar": string}
• array{0: int, 1?: int} (key 1 is optional in the array)
• array{int, int} (keys are 0 and 1)
• array{foo: int, bar: string} (quotes around array keys aren’t necessary)

This is different from general arrays that mandate that all the keys and values must be of a specific homogeneous type. Array shapes allow each key and value to be different.

Literals and constants #

PHPStan allows specifying scalar values as types in PHPDocs:

• 234 (integers)
• 1.0 (floats)
• 'foo'|'bar' (strings; types can be combined with others)

Constant enumerations are also supported:

• Foo::SOME_CONSTANT
• Foo::SOME_CONSTANT|Bar::OTHER_CONSTANT
• self::SOME_* (all constants on self that start with SOME_)
• Foo::* (all constants on Foo)

Callables #

The callable typehint has been in PHP for a long time. But it doesn’t allow enforcing specific callback signatures. However, PHPStan allows and enforce specific signatures in PHPDocs:

• callable(int, int): string (accepts two integers, returns a string)
• callable(int, int=): string (second parameter is optional)
• callable(int $foo, string $bar): void (accepts an integer and a string, doesn’t return anything; parameter names are optional and insignificant)
• callable(string &$bar): mixed (accepts a string parameter passed by reference, returns mixed)
• callable(float ...$floats): (int|null) (accepts multiple variadic float arguments, returns integer or null)

Parameter types and return type are required. Use mixed if you don’t want to use a more specific type.

Bottom type #

All of these names are equivalent:

• never
• never-return
• never-returns
• no-return

Marking a function or a method as @return never tells PHPStan the function always throws an exception, or contains a way to end the script execution, like die() or exit(). This is useful when solving undefined variables.

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