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761 lines
20 KiB
Markdown
761 lines
20 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.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.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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- [`@mixin`](#mixins)
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Used to tell Psalm that the current class proxies the methods and properties of the referenced class.
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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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### @mixins
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Adding `@mixin` to a classes docblock tells Psalm that the class proxies will proxy the methods and properties of the referenced class.
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```php
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class A
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{
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public string $a = 'A';
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public function doA(): void
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{
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}
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}
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/**
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* @mixin A
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*/
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class B
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{
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public string $b = 'B';
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public function doB(): void
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{
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}
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public function __call($name, $arguments)
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{
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(new A())->$name(...$arguments);
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}
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public function __get($name)
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{
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(new A())->$name;
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}
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}
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$b = new B();
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$b->doB();
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$b->doA(); // works
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echo $b->b;
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echo $b->a; // works
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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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### `@psalm-consistent-constructor`
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See [UnsafeInstantiation](../running_psalm/issues/UnsafeInstantiation.md)
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### `@psalm-consistent-templates`
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See [UnsafeGenericInstantiation](../running_psalm/issues/UnsafeGenericInstantiation.md)
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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-ignore-var`
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This annotation is used to ignore the `@var` annotation written in the same docblock. Some IDEs don't fully understand complex types like generics. To take advantage of such IDE's auto-completion, you may sometimes want to use explicit `@var` annotations even when psalm can infer the type just fine. This weakens the effectiveness of type checking in many cases since the explicit `@var` annotation overrides the types inferred by psalm. As psalm ignores the `@var` annotation which is co-located with `@psalm-ignore-var`, IDEs can use the type specified by the `@var` for auto-completion, while psalm can still use its own inferred type for type checking.
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```php
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<?php
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/** @return iterable<array-key,\DateTime> $f */
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function getTimes(int $n): iterable {
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while ($n--) {
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yield new \DateTime();
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}
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};
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/**
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* @var \Datetime[] $times
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* @psalm-ignore-var
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*/
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$times = getTimes(3);
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// this trace shows "iterable<array-key, DateTime>" instead of "array<array-key, Datetime>"
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/** @psalm-trace $times */
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foreach ($times as $time) {
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echo $time->format('Y-m-d H:i:s.u') . PHP_EOL;
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}
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```
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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`, `@psalm-assert-if-false`, `@psalm-if-this-is` and `@psalm-this-out`
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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`, `@psalm-no-seal-properties`, `@seal-properties`, `@no-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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This is automatically enabled with the configuration option `sealAllProperties` and can be disabled for a class with `@psalm-no-seal-properties`
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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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* @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-seal-methods`, `@psalm-no-seal-methods`, `@seal-methods`, `@no-seal-methods`
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If you have a magic method caller, you can use `@psalm-seal-methods` to instruct Psalm to disallow calling any methods not contained in a list of `@method` annotations.
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This is automatically enabled with the configuration option `sealAllMethods` and can be disabled for a class with `@psalm-no-seal-methods`
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```php
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<?php
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/**
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* @method foo(): string
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* @seal-methods
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*/
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class A {
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public function __call(string $name, array $args) {
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if ($name === "foo") {
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return "hello";
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}
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}
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}
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$a = new A();
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$b = $a->bar(); // this call fails
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```
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### `@psalm-internal`
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Used to mark a class, property or function as internal to a given namespace. Psalm treats this slightly differently to
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the PHPDoc `@internal` tag. For `@internal`, an issue is raised if the calling code is in a namespace completely
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unrelated to the namespace of the calling code, i.e. not sharing the first element of the namespace.
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In contrast for `@psalm-internal`, the docblock line must specify a namespace. An issue is raised if the calling code
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is not within the given namespace.
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```php
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<?php
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namespace A\B {
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/**
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* @internal
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* @psalm-internal A\B
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*/
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class Foo { }
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}
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namespace A\B\C {
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class Bat {
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public function batBat(): void {
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$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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This requires that the return value depend only on the instance's properties. For example, `random_int` is considered
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mutating here because it mutates the random number generator's internal state.
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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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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).
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To see it, you can set the global `errorLevel` to 1, or invoke Psalm with
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`--show-info=true`, but both these solutions will probably result in a lot of
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output. Another solution is to selectively bump the error level of the issue,
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so that you only get one more error:
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```xml
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<!-- psalm.xml -->
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<issueHandlers>
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<Trace errorLevel="error"/>
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</issueHandlers>
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```
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### `@psalm-check-type`
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You can use this annotation to ensure the inferred type matches what you expect.
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```php
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<?php
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/** @psalm-check-type $foo = int */
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$foo = 1; // No issue
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/** @psalm-check-type $bar = int */
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$bar = "not-an-int"; // Checked variable $bar = int does not match $bar = 'not-an-int'
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```
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### `@psalm-check-type-exact`
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||
Like `@psalm-check-type`, but checks the exact type of the variable without allowing subtypes.
|
||
|
||
```php
|
||
<?php
|
||
|
||
/** @psalm-check-type-exact $foo = int */
|
||
$foo = 1; // Checked variable $foo = int does not match $foo = 1
|
||
```
|
||
|
||
### `@psalm-taint-*`
|
||
|
||
See [Security Analysis annotations](../security_analysis/annotations.md).
|
||
|
||
### `@psalm-type`
|
||
|
||
This allows you to define an alias for another type.
|
||
|
||
```php
|
||
<?php
|
||
/**
|
||
* @psalm-type PhoneType = array{phone: string}
|
||
*/
|
||
class Phone {
|
||
/**
|
||
* @psalm-return PhoneType
|
||
*/
|
||
public function toArray(): array {
|
||
return ["phone" => "Nokia"];
|
||
}
|
||
}
|
||
```
|
||
|
||
### `@psalm-import-type`
|
||
|
||
You can use this annotation to import a type defined with [`@psalm-type`](#psalm-type) if it was defined somewhere else.
|
||
|
||
```php
|
||
<?php
|
||
/**
|
||
* @psalm-import-type PhoneType from Phone
|
||
*/
|
||
class User {
|
||
/**
|
||
* @psalm-return PhoneType
|
||
*/
|
||
public function toArray(): array {
|
||
return array_merge([], (new Phone())->toArray());
|
||
}
|
||
}
|
||
```
|
||
|
||
You can also alias a type when you import it:
|
||
|
||
```php
|
||
<?php
|
||
/**
|
||
* @psalm-import-type PhoneType from Phone as MyPhoneTypeAlias
|
||
*/
|
||
class User {
|
||
/**
|
||
* @psalm-return MyPhoneTypeAlias
|
||
*/
|
||
public function toArray(): array {
|
||
return array_merge([], (new Phone())->toArray());
|
||
}
|
||
}
|
||
```
|
||
|
||
### `@psalm-require-extends`
|
||
|
||
The `@psalm-require-extends` annotation allows you to define the requirements that a trait imposes on the using class.
|
||
|
||
```php
|
||
<?php
|
||
abstract class DatabaseModel {
|
||
// methods, properties, etc.
|
||
}
|
||
|
||
/**
|
||
* @psalm-require-extends DatabaseModel
|
||
*/
|
||
trait SoftDeletingTrait {
|
||
// useful but scoped functionality, that depends on methods/properties from DatabaseModel
|
||
}
|
||
|
||
|
||
class MyModel extends DatabaseModel {
|
||
// valid
|
||
use SoftDeletingTrait;
|
||
}
|
||
|
||
class NormalClass {
|
||
// triggers an error
|
||
use SoftDeletingTrait;
|
||
}
|
||
```
|
||
|
||
### `@psalm-require-implements`
|
||
|
||
Behaves the same way as `@psalm-require-extends`, but for interfaces.
|
||
|
||
### `@no-named-arguments`
|
||
|
||
This will prevent access to the function or method tagged with named parameters (by emitting a `NamedArgumentNotAllowed` issue).
|
||
|
||
Incidentally, it will change the inferred type for the following code:
|
||
```php
|
||
<?php
|
||
function a(int ...$a){
|
||
var_dump($a);
|
||
}
|
||
```
|
||
The type of `$a` is `array<array-key, int>` without `@no-named-arguments` but becomes `list<int>` with it, because it excludes the case where the offset would be a string with the name of the parameter
|
||
|
||
### `@psalm-ignore-variable-property` and `@psalm-ignore-variable-method`
|
||
|
||
Instructs Psalm to ignore variable property fetch / variable method call when looking for dead code.
|
||
```php
|
||
class Foo
|
||
{
|
||
// this property can be deleted by Psalter,
|
||
// as potential reference in get() is ignored
|
||
public string $bar = 'bar';
|
||
|
||
public function get(string $name): mixed
|
||
{
|
||
/** @psalm-ignore-variable-property */
|
||
return $this->{$name};
|
||
}
|
||
}
|
||
```
|
||
When Psalm encounters variable property, it treats all properties in given class as potentially referenced.
|
||
With `@psalm-ignore-variable-property` annotation, this reference is ignored.
|
||
|
||
While `PossiblyUnusedProperty` would be emitted in both cases, using `@psalm-ignore-variable-property`
|
||
would allow [Psalter](../manipulating_code/fixing.md) to delete `Foo::$bar`.
|
||
|
||
`@psalm-ignore-variable-method` behaves the same way, but for variable method calls.
|
||
|
||
### `@psalm-yield`
|
||
|
||
Used to specify the type of value which will be sent back to a generator when an annotated object instance is yielded.
|
||
|
||
```php
|
||
<?php
|
||
/**
|
||
* @template-covariant TValue
|
||
* @psalm-yield TValue
|
||
*/
|
||
interface Promise {}
|
||
|
||
/**
|
||
* @template-covariant TValue
|
||
* @template-implements Promise<TValue>
|
||
*/
|
||
class Success implements Promise {
|
||
/**
|
||
* @psalm-param TValue $value
|
||
*/
|
||
public function __construct($value) {}
|
||
}
|
||
|
||
/**
|
||
* @return Promise<string>
|
||
*/
|
||
function fetch(): Promise {
|
||
return new Success('{"data":[]}');
|
||
}
|
||
|
||
function (): Generator {
|
||
$data = yield fetch();
|
||
|
||
// this is fine, Psalm knows that $data is a string
|
||
return json_decode($data);
|
||
};
|
||
```
|
||
This annotation supports only generic types, meaning that e.g. `@psalm-yield string` would be ignored.
|
||
|
||
### `@api`, `@psalm-api`
|
||
|
||
Used to tell Psalm that a class or method is used, even if no references to it can be
|
||
found. Unused issues will be suppressed.
|
||
|
||
For example, in frameworks, controllers are often invoked "magically" without
|
||
any explicit references to them in your code. You should mark these classes with
|
||
`@psalm-api`.
|
||
```php
|
||
/**
|
||
* @psalm-api
|
||
*/
|
||
class UnreferencedClass {}
|
||
```
|
||
|
||
### `@psalm-inheritors`
|
||
|
||
Used to tell Psalm that a class can only be extended by a certain subset of classes.
|
||
|
||
For example,
|
||
```php
|
||
<?php
|
||
/**
|
||
* @psalm-inheritors FooClass|BarClass
|
||
*/
|
||
class BaseClass {}
|
||
class FooClass extends BaseClass {}
|
||
class BarClass extends BaseClass {}
|
||
class BazClass extends BaseClass {} // this is an error
|
||
```
|
||
|
||
## Type Syntax
|
||
|
||
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).
|
||
|
||
A detailed write-up is found in [Typing in Psalm](typing_in_psalm.md)
|