Opting out of Named Parameters in PHP 8.0

PHP 8.0 brings Named Parameters support to PHP.

With named parameters, the names of the function/method names become part of the API, and changing the parameter name will be breaking change.

---

function findSomething(string $heystack, string $needle) {}

With a function declaration like this, named parameter allows to call the findSomething function with explicitly declaring the parameters, without having to depend on the order of parameters.

findSomething(heystack: "FooBar", needle: "Bar");

Now, if the author of the findSomething notices the typo in heystack word, and decides to fix it with haystack, all code that used named parameters feature will raise a fatal error:

function findSomething(string $haystack, string $needle) {}
findSomething(heystack: "FooBar", needle: "Bar");

Fatal error: Uncaught Error: Unknown named parameter $heystack in ...:...

Note that in case of an interface/inheritance chain, PHP considers parameter names of the called class and all its parents.

---

@no-named-arguments

Over at Roave/BackwardCompatibilityCheck project, a discussion lead to a new @no-named-arguments DocBlock attribute (which is not the same as PHP 8.0 attributes as it is a PHP 8.0 feature) that might add support to explicitly declare that the code does not provide backwards-compatibility promise for parameter names, discouraging the use of named parameters with it.

If this DocBlock attribute is present, it means the author explicitly declares that there will be no backwards compatibility promise for the parameter names, and users of the library should not use named parameters calling pattern for functions/methods from that library.

/**
 * @no-named-arguments
 */
function findSomething(string $haystack, string $needle) {}

It is also possible to set a custom description:

/**
 * @no-named-arguments No BC promise.
 */
function findSomething(string $haystack, string $needle) {}

Adoption of @no-named-arguments

Static Analyzers

• Psalm: Full support from version 4.1.1
• Phan: See phan/phan#4152
• BackwardCompatibilityCheck: See Roave/BackwardCompatibilityCheck#264

Projects

From the top 100 most downloaded Composer projects:

• PHPUnit: Parameter names are not covered by the backward compatibility promise for PHPUnit

IDEs

PHPStorm will support named parameters in PHPStorm 2020.3.

It appears that there is no support for @no-named-arguments attribute in PHPStorm or any other IDE yet.