Valid Class Name

A valid class name seen from the context where this type is mentioned. Thus this may be either a Fully Qualified Class Name (FQCN) or if present in a namespace a local name.

The element to which this type applies is either an instance of this class or an instance of a class that is a (sub-)child to the given class.

Example:

@param \My\Namespace\Class
@return Exception

Keyword

A keyword defining the purpose of this type. Not every element is determined by a class but still worth of a classification to assist the developer in understanding the code covered by the PHPDoc.

The following keywords are recognized:

1. string, the element to which this type applies is a string of binary characters.
2. integer or int, the element to which this type applies is a whole number or integer.
3. boolean or bool, the element to which this type applies only has state true or false.
4. float or double, the element to which this type applies is a continuous, or real, number.
5. object, the element to which this type applies is the instance of an undetermined class.
6. mixed, the element to which this type applies can be of any type as specified here. It is not known on compile time which type will be used.
7. array, the element to which this type applies is an array of values, see the section on Arrays for more details.
8. resource, the element to which this type applies is a resource per the definition of PHP at https://www.php.net/language.types.resource.

9. void, this type is commonly only used when defining the return type of a method or function. The basic definition is that the element indicated with this type does not contain a value and the user should not rely on any retrieved value.

   For example:

   /**
    * @return void
    */
   function outputHello()
   {
       echo 'Hello world';
   }

   In the example above no return statement is specified and thus is the return value not determined.

   Example 2:

   /**
    * @param boolean $quiet when true 'Hello world' is not echo-ed.
    *
    * @return void
    */
   function outputHello($quiet)
   {
       if ($quiet) {
           return;
       }
       echo 'Hello world';
   }

   In this example the function contains a return statement without a given value. Because there is no actual value specified does this also constitute as type 'void'.

10. null, the element to which this type applies is a NULL value or, in technical terms, does not exist.

    A big difference compared to void is that this type is used in any situation where the described element may at any given time contain an explicit NULL value.

    Example:

    /**
     * @return null
     */
    function foo()
    {
        echo 'Hello world';
        return null;
    }

    This type is commonly used in conjunction with another type to indicate that it is possible that nothing may be returned.

    Example:

    /**
     * @param boolean $create_new When true returns a new stdClass.
     *
     * @return stdClass|null
     */
    function foo($create_new)
    {
        if ($create_new) {
            return new stdClass();
        }
    
        return null;
    }

11. callable, the element to which this type applies is a pointer to a function call. This may be any type of callback as defined in the PHP manual at https://www.php.net/language.types.callable.

12. false or true, the element to which this type applies will have the value true or false. No other value will be returned from this element.

    This type is commonly used in conjunction with another type to indicate that it is possible that true or false may be returned instead of an instance of the other type.

13. self, the element to which this type applies is of the same Class, or any of its children, as which the documented element is originally contained.

    For example:

    Method C() is contained in class A. The DocBlock states that its return value is of type self. As such method C() returns an instance of class A.

    This may lead to confusing situations when inheritance is involved.

    For example (previous example situation still applies):

    Class B extends Class A and does not redefine method C(). As such it is possible to invoke method C() from class B.

    In this situation ambiguity may arise as self could be interpreted as either class A or B. In these cases self MUST be interpreted as being an instance of the Class where the DocBlock containing the self type is written or any of its child classes.

    In the examples above self MUST always refer to class A or B, since it is defined with method C() in class A.

    If method C() was to be redefined in class B, including the type definition in the DocBlock, then self would refer to class B or any of its children.

14. scalar, the element to which this type applies is of any scalar type specifically: string, float, int, bool