#### 25.2.15 documentation, (setf documentation) [Standard Generic Function]

#### Syntax::

`documentation` x doc-type ⇒ documentation

`(setf documentation)` new-value x doc-type ⇒ new-value

#### Argument Precedence Order::

doc-type, object

#### Method Signatures::

#### Functions, Macros, and Special Forms

documentation (x `function`) (doc-type (eql ’t))
(setf documentation) new-value(x `function`) (doc-type (eql ’t))

documentation (x `function`) (doc-type (eql ’function))
(setf documentation) new-value(x `function`) (doc-type (eql ’function))

documentation (x `list`) (doc-type (eql ’function))
(setf documentation) new-value(x `list`) (doc-type (eql ’function))

documentation (x `list`) (doc-type (eql ’compiler-macro))
(setf documentation) new-value(x `list`) (doc-type (eql ’compiler-macro))

documentation (x `symbol`) (doc-type (eql ’function))
(setf documentation) new-value(x `symbol`) (doc-type (eql ’function))

documentation (x `symbol`) (doc-type (eql ’compiler-macro))
(setf documentation) new-value(x `symbol`) (doc-type (eql ’compiler-macro))

documentation (x `symbol`) (doc-type (eql ’setf))
(setf documentation) new-value(x `symbol`) (doc-type (eql ’setf))

#### Method Combinations

documentation (x `method-combination`) (doc-type (eql ’t))
(setf documentation) new-value(x `method-combination`) (doc-type (eql ’t))

documentation (x `method-combination`) (doc-type (eql ’method-combination))
(setf documentation) new-value(x `method-combination`) (doc-type (eql ’method-combination))

documentation (x `symbol`) (doc-type (eql ’method-combination))
(setf documentation) new-value(x `symbol`) (doc-type (eql ’method-combination))

#### Methods

documentation (x `standard-method`) (doc-type (eql ’t))
(setf documentation) new-value(x `standard-method`) (doc-type (eql ’t))

#### Packages

documentation (x `package`) (doc-type (eql ’t))
(setf documentation) new-value(x `package`) (doc-type (eql ’t))

#### Types, Classes, and Structure Names

documentation (x `standard-class`) (doc-type (eql ’t))
(setf documentation) new-value(x `standard-class`) (doc-type (eql ’t))

documentation (x `standard-class`) (doc-type (eql ’type))
(setf documentation) new-value(x `standard-class`) (doc-type (eql ’type))

documentation (x `structure-class`) (doc-type (eql ’t))
(setf documentation) new-value(x `structure-class`) (doc-type (eql ’t))

documentation (x `structure-class`) (doc-type (eql ’type))
(setf documentation) new-value(x `structure-class`) (doc-type (eql ’type))

documentation (x `symbol`) (doc-type (eql ’type))
(setf documentation) new-value(x `symbol`) (doc-type (eql ’type))

documentation (x `symbol`) (doc-type (eql ’structure))
(setf documentation) new-value(x `symbol`) (doc-type (eql ’structure))

#### Variables

documentation (x `symbol`) (doc-type (eql ’variable))
(setf documentation) new-value(x `symbol`) (doc-type (eql ’variable))

#### Arguments and Values::

x—an object.

doc-type—a symbol.

documentation—a string, or nil.

new-value—a string.

#### Description::

The generic function documentation returns the documentation string associated with the given object if it is available; otherwise it returns nil.

The generic function `(setf documentation)` updates the documentation string associated with x to new-value. If x is a list, it must be of the form `(setf symbol)`.

Documentation strings are made available for debugging purposes. Conforming programs are permitted to use documentation strings when they are present, but should not depend for their correct behavior on the presence of those documentation strings. An implementation is permitted to discard documentation strings at any time for implementation-defined reasons.

The nature of the documentation string returned depends on the doc-type, as follows:

compiler-macro

  Returns the documentation string of the compiler macro whose name is the function name x.

function

  If x is a function name, returns the documentation string of the function, macro, or special operator whose name is x.

  If x is a function, returns the documentation string associated with x.

method-combination

  If x is a symbol, returns the documentation string of the method combination whose name is x.

  If x is a method combination, returns the documentation string associated with x.

setf

  Returns the documentation string of

  the setf expander

  whose name is the symbol x.

structure

  Returns the documentation string associated with the structure name x.

t

  Returns a documentation string specialized on the class of the argument x itself. For example, if x is a function, the documentation string associated with the function x is returned.

type

  If x is a symbol, returns the documentation string of the class whose name is the symbol x, if there is such a class. Otherwise, it returns the documentation string of the type which is the type specifier symbol x.

  If x is a structure class or standard class, returns the documentation string associated with the class x.

variable

  Returns the documentation string of the dynamic variable or constant variable whose name is the symbol x.

A conforming implementation or a conforming program may extend the set of symbols that are acceptable as the doc-type.

#### Notes::

This standard prescribes no means to retrieve the documentation strings for individual slots specified in a defclass form, but implementations might still provide debugging tools and/or programming language extensions which manipulate this information. Implementors wishing to provide such support are encouraged to consult the Metaobject Protocol for suggestions about how this might be done.