Many tags use a Type as part of their definition (such as the @return tag).
These types differ from the official PHP definition to be able to represent all
kinds of data.
A complete definition will be given of these types and what they represent in
the following sections.
When a Type is used the user will expect a value, or set of values, as
detailed below.
Atomic (singular) type
The supported atomic types are either a valid class name or keyword.
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.
Most of these keywords are allowed as class names in PHP and as
such are hard to distinguish from real classes. As such the keywords MUST
be lowercase, as most class names start with an uppercase first character,
and you SHOULD NOT use classes with these names in your code.
There are more reasons to not name classes with the names of these
keywords but that falls beyond the scope of this specification.
The following keywords are recognized:
string, the element to which this type applies is a string of
binary characters.
integer or int, the element to which this type applies is a whole
number or integer.
boolean or bool, the element to which this type applies only has
state true or false.
float or double, the element to which this type applies is a
continuous, or real, number.
object, the element to which this type applies is the instance of an
undetermined class.
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.
array, the element to which this type applies is an array of values,
see the section on Arrays for more details.
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.
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'.
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.
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;
}
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.
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.
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.
scalar, the element to which this type applies is of any scalar type
specifically: string, float, int, bool
Multiple types
When the Type consists of multiple (sub-)types then these MUST be
separated with the vertical bar sign (|).
For example:
@return int|null
Arrays
The value represented by Type can be an array. The type MUST be defined
following the format of one of the following options:
unspecified, no definition of the contents of the represented array is given.
Example: @return array
specified containing a single type, the Type definition informs
the reader of the type of each array element. Only one Type is then
expected as element for a given array.
Example: @return int[]
Please note that mixed is also a single type and with this keyword it is
possible to indicate that each array element contains any possible type.
specified containing multiple types, the Type definition informs the reader
of the type of each array element. Each element can be of any of the given
types.
Example: @return (int|string)[]
many IDEs probably do not support this notation yet.