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515 lines
13 KiB
Markdown
515 lines
13 KiB
Markdown
# Supported docblock annotations
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Psalm supports a wide range of docblock annotations.
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## PHPDoc tags
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Psalm uses the following PHPDoc tags to understand your code:
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- [`@var`](https://docs.phpdoc.org/latest/guide/references/phpdoc/tags/var.html)
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Used for specifying the types of properties and variables@
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- [`@return`](https://docs.phpdoc.org/latest/guide/references/phpdoc/tags/return.html)
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Used for specifying the return types of functions, methods and closures
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- [`@param`](https://docs.phpdoc.org/latest/guide/references/phpdoc/tags/param.html)
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Used for specifying types of parameters passed to functions, methods and closures
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- [`@property`](https://docs.phpdoc.org/latest/guide/references/phpdoc/tags/property.html)
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Used to specify what properties can be accessed on an object that uses `__get` and `__set`
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- [`@property-read`](https://docs.phpdoc.org/latest/guide/references/phpdoc/tags/property-read.html)
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Used to specify what properties can be read on object that uses `__get`
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- [`@property-write`](https://docs.phpdoc.org/latest/guide/references/phpdoc/tags/property-write.html)
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Used to specify what properties can be written on object that uses `__set`
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- [`@method`](https://docs.phpdoc.org/latest/guide/references/phpdoc/tags/method.html)
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Used to specify which magic methods are available on object that uses `__call`.
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- [`@deprecated`](https://docs.phpdoc.org/latest/guide/references/phpdoc/tags/deprecated.html)
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Used to mark functions, methods, classes and interfaces as being deprecated
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- [`@internal`](https://docs.phpdoc.org/latest/guide/references/phpdoc/tags/internal.html)
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used to mark classes, functions and properties that are internal to an application or library.
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### Off-label usage of the `@var` tag
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The `@var` tag is supposed to only be used for properties. Psalm, taking a lead from PHPStorm and other static analysis tools, allows its use inline in the form `@var Type [VariableReference]`.
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If `VariableReference` is provided, it should be of the form `$variable` or `$variable->property`. If used above an assignment, Psalm checks whether the `VariableReference` matches the variable being assigned. If they differ, Psalm will assign the `Type` to `VariableReference` and use it in the expression below.
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If no `VariableReference` is given, the annotation tells Psalm that the right hand side of the expression, whether an assignment or a return, is of type `Type`.
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```php
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<?php
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/** @var string */
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$a = $_GET['foo'];
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/** @var string $b */
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$b = $_GET['bar'];
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function bat(): string {
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/** @var string */
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return $_GET['bat'];
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}
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```
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## Psalm-specific tags
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There are a number of custom tags that determine how Psalm treats your code.
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### `@param-out`, `@psalm-param-out`
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This is used to specify that a by-ref type is different from the one that entered. In the function below the first param can be null, but once the function has executed the by-ref value is not null.
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```php
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<?php
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/**
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* @param-out string $s
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*/
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function addFoo(?string &$s) : void {
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if ($s === null) {
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$s = "hello";
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}
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$s .= "foo";
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}
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```
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### `@psalm-var`, `@psalm-param`, `@psalm-return`, `@psalm-property`, `@psalm-property-read`, `@psalm-property-write`, `@psalm-method`
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When specifying types in a format not supported by phpDocumentor ([but supported by Psalm](#type-syntax)) you may wish to prepend `@psalm-` to the PHPDoc tag, so as to avoid confusing your IDE. If a `@psalm`-prefixed tag is given, Psalm will use it in place of its non-prefixed counterpart.
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### `@psalm-suppress SomeIssueName`
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This annotation is used to suppress issues. It can be used in function docblocks, class docblocks and also inline, applying to the following statement.
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Function docblock example:
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```php
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<?php
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/**
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* @psalm-suppress PossiblyNullOperand
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*/
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function addString(?string $s) {
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echo "hello " . $s;
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}
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```
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Inline example:
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```php
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<?php
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function addString(?string $s) {
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/** @psalm-suppress PossiblyNullOperand */
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echo "hello " . $s;
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}
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```
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`@psalm-suppress all` can be used to suppress all issues instead of listing them individually.
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### `@psalm-assert`, `@psalm-assert-if-true` and `@psalm-assert-if-false`
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See [Adding assertions](adding_assertions.md).
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### `@psalm-ignore-nullable-return`
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This can be used to tell Psalm not to worry if a function/method returns null. It’s a bit of a hack, but occasionally useful for scenarios where you either have a very high confidence of a non-null value, or some other function guarantees a non-null value for that particular code path.
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```php
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<?php
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class Foo {}
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function takesFoo(Foo $f): void {}
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/** @psalm-ignore-nullable-return */
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function getFoo(): ?Foo {
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return rand(0, 10000) > 1 ? new Foo() : null;
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}
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takesFoo(getFoo());
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```
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### `@psalm-ignore-falsable-return`
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This provides the same, but for `false`. Psalm uses this internally for functions like `preg_replace`, which can return false if the given input has encoding errors, but where 99.9% of the time the function operates as expected.
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### `@psalm-seal-properties`
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If you have a magic property getter/setter, you can use `@psalm-seal-properties` to instruct Psalm to disallow getting and setting any properties not contained in a list of `@property` (or `@property-read`/`@property-write`) annotations.
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```php
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<?php
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/**
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* @property string $foo
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* @psalm-seal-properties
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*/
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class A {
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public function __get(string $name): ?string {
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if ($name === "foo") {
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return "hello";
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}
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}
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public function __set(string $name, $value): void {}
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}
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$a = new A();
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$a->bar = 5; // this call fails
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```
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### `@psalm-internal`
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Used to mark a class, property or function as internal to a given namespace. Psalm treats this slightly differently to
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the PHPDoc `@internal` tag. For `@internal`, an issue is raised if the calling code is in a namespace completely
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unrelated to the namespace of the calling code, i.e. not sharing the first element of the namespace.
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In contrast for `@psalm-internal`, the docbloc line must specify a namespace. An issue is raised if the calling code
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is not within the given namespace.
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```php
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<?php
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namespace A\B {
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/**
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* @internal
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* @psalm-internal A\B
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*/
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class Foo { }
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}
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namespace A\B\C {
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class Bat {
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public function batBat(): void {
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$a = new \A\B\Foo(); // this is fine
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}
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}
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}
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namespace A\C {
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class Bat {
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public function batBat(): void {
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$a = new \A\B\Foo(); // error
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}
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}
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}
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```
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### `@psalm-readonly` and `@readonly`
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Used to annotate a property that can only be written to in its defining class's constructor.
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```php
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<?php
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class B {
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/** @readonly */
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public string $s;
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public function __construct(string $s) {
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$this->s = $s;
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}
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}
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$b = new B("hello");
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echo $b->s;
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$b->s = "boo"; // disallowed
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```
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### `@psalm-mutation-free`
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Used to annotate a class method that does not mutate state, either internally or externally of the class's scope.
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```php
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<?php
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class D {
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private string $s;
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public function __construct(string $s) {
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$this->s = $s;
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}
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/**
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* @psalm-mutation-free
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*/
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public function getShort() : string {
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return substr($this->s, 0, 5);
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}
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/**
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* @psalm-mutation-free
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*/
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public function getShortMutating() : string {
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$this->s .= "hello"; // this is a bug
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return substr($this->s, 0, 5);
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}
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}
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```
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### `@psalm-external-mutation-free`
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Used to annotate a class method that does not mutate state externally of the class's scope.
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```php
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<?php
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class E {
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private string $s;
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public function __construct(string $s) {
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$this->s = $s;
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}
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/**
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* @psalm-external-mutation-free
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*/
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public function getShortMutating() : string {
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$this->s .= "hello"; // this is fine
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return substr($this->s, 0, 5);
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}
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/**
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* @psalm-external-mutation-free
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*/
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public function save() : void {
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file_put_contents("foo.txt", $this->s); // this is a bug
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}
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}
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```
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### `@psalm-immutable`
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Used to annotate a class where every property is treated by consumers as `@psalm-readonly` and every instance method is treated as `@psalm-mutation-free`.
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```php
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<?php
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/**
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* @psalm-immutable
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*/
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abstract class Foo
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{
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public string $baz;
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abstract public function bar(): int;
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}
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/**
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* @psalm-immutable
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*/
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final class ChildClass extends Foo
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{
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public function __construct(string $baz)
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{
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$this->baz = $baz;
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}
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public function bar(): int
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{
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return 0;
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}
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}
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$anonymous = new /** @psalm-immutable */ class extends Foo
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{
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public string $baz = "B";
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public function bar(): int
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{
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return 1;
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}
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};
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```
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### `@psalm-pure`
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Used to annotate a [pure function](https://en.wikipedia.org/wiki/Pure_function) - one whose output is just a function of its input.
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```php
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<?php
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class Arithmetic {
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/** @psalm-pure */
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public static function add(int $left, int $right) : int {
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return $left + $right;
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}
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/** @psalm-pure - this is wrong */
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public static function addCumulative(int $left) : int {
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/** @var int */
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static $i = 0; // this is a side effect, and thus a bug
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$i += $left;
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return $i;
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}
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}
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echo Arithmetic::add(40, 2);
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echo Arithmetic::add(40, 2); // same value is emitted
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echo Arithmetic::addCumulative(3); // outputs 3
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echo Arithmetic::addCumulative(3); // outputs 6
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```
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### `@pure-callable`
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On the other hand, `pure-callable` can be used to denote a callable which needs to be pure.
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```php
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/**
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* @param pure-callable(mixed): int $callback
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*/
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function foo(callable $callback) {...}
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// this fails since random_int is not pure
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foo(
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/** @param mixed $p */
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fn($p) => random_int(1, 2)
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);
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```
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### `@psalm-allow-private-mutation`
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Used to annotate readonly properties that can be mutated in a private context. With this, public properties can be read from another class but only be mutated within a method of its own class.
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```php
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<?php
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class Counter {
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/**
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* @readonly
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* @psalm-allow-private-mutation
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*/
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public int $count = 0;
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public function increment() : void {
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$this->count++;
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}
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}
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$counter = new Counter();
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echo $counter->count; // outputs 0
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$counter->increment(); // Method can mutate property
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echo $counter->count; // outputs 1
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$counter->count = 5; // This will fail, as it's mutating a property directly
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```
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### `@psalm-readonly-allow-private-mutation`
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This is a shorthand for the property annotations `@readonly` and `@psalm-allow-private-mutation`.
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```php
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<?php
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class Counter {
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/**
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* @psalm-readonly-allow-private-mutation
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*/
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public int $count = 0;
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public function increment() : void {
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$this->count++;
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}
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}
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$counter = new Counter();
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echo $counter->count; // outputs 0
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$counter->increment(); // Method can mutate property
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echo $counter->count; // outputs 1
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$counter->count = 5; // This will fail, as it's mutating a property directly
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```
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### `@psalm-trace`
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You can use this annotation to trace inferred type (applied to the *next* statement).
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```php
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<?php
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/** @psalm-trace $username */
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$username = $_GET['username']; // prints something like "test.php:4 $username: mixed"
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```
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*Note*: it throws [special low-level issue](../running_psalm/issues/Trace.md), so you have to set errorLevel to 1, override it in config or invoke Psalm with `--show-info=true`.
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### `@psalm-taint-*`
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See [Security Analysis annotations](../security_analysis/annotations.md).
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### `@psalm-type`
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This allows you to define an alias for another type.
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```php
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<?php
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/**
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* @psalm-type PhoneType = array{phone: string}
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*/
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class Phone {
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/**
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* @psalm-return PhoneType
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*/
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public function toArray(): array {
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return ["phone" => "Nokia"];
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}
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}
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```
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### `@psalm-import-type`
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You can use this annotation to import a type defined with [`@psalm-type`](#psalm-type) if it was defined somewhere else.
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```php
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<?php
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/**
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* @psalm-import-type PhoneType from Phone
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*/
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class User {
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/**
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* @psalm-return PhoneType
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*/
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public function toArray(): array {
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return array_merge([], (new Phone())->toArray());
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}
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}
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```
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You can also alias a type when you import it:
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```php
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<?php
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/**
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* @psalm-import-type PhoneType from Phone as MyPhoneTypeAlias
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*/
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class User {
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/**
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* @psalm-return MyPhoneTypeAlias
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*/
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public function toArray(): array {
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return array_merge([], (new Phone())->toArray());
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}
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}
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```
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### `@psalm-require-extends`
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The @psalm-require-extends-annotation allows you to define a requirements that a trait imposes on the using class.
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```php
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abstract class DatabaseModel {
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// methods, properties, etc.
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}
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/**
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* @psalm-require-extends DatabaseModel
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*/
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trait SoftDeletingTrait {
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// useful but scoped functionality, that depends on methods/properties from DatabaseModel
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}
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class MyModel extends DatabaseModel {
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// valid
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use SoftDeletingTrait;
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}
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class NormalClass {
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// triggers an error
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use SoftDeletingTrait;
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}
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```
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### `@psalm-require-implements`
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Behaves the same way as `@psalm-require-extends`, but for interfaces.
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## Type Syntax
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Psalm supports PHPDoc’s [type syntax](https://docs.phpdoc.org/latest/guide/guides/types.html), and also the [proposed PHPDoc PSR type syntax](https://github.com/php-fig/fig-standards/blob/master/proposed/phpdoc.md#appendix-a-types).
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A detailed write-up is found in [Typing in Psalm](typing_in_psalm.md)
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