Brief Guide to CLOS: Quick reference

## 8. Quick reference

Square brackets ("[" and "]") indicate optional elements. A vertical bar ("|") indicates an alternative. Thing* means zero or more occurrence of thing, thing+ means one or more occurrence. "{" and "}" are used for grouping.

## 8.1 Defining a class

> `

>     (DEFCLASS class-name (superclass-name*)
>       (slot-description*))

> `

## 8.2 Slot descriptions

`(slot-name slot-option*)`

:ACCESSOR

  function-name

:INITFORM

  expression

:INITARG

  keyword-symbol

## 8.3 Making instances

`(MAKE-INSTANCE class {initarg value}*)`

## 8.4 Method definitions

`(DEFMETHOD generic-function-name [qualifier] specialized-lambda-list form*)` where

- generic-function-name is a symbol
- qualifier is :BEFORE, :AFTER, :AROUND, or else omitted
- specialized-lambda-list is ( {variable | (variable class-name)}* )

## 8.5 Some functions

### (DESCRIBE instance)

### (DESCRIBE class)

### (FIND-CLASS class-name) -> class

As in:

> `

>     <cl> (FIND-CLASS 'teacher)

>     #<STANDARD-CLASS TEACHER {90374C5}>

> `

### (CLASS-NAME class) -> symbol

As in:

> `

>     <cl> (class-name (find-class 'teacher))

>     TEACHER

> `

### (CLASS-PRECEDENCE-LIST class) -> list of classes

[This is called `(CLOS::CLASS-PRECEDENCE-LIST class)` in CLISP.]

[This is called `(PCL:CLASS-PRECEDENCE-LIST class)` in CMUCL.]

As in (CMUCL):

> `

>     * (pcl:class-precedence-list  (find-class 'teacher))

>     (#<Standard-Class TEACHER {902FF6D}> #<Standard-Class PERSON {9010ADD}>
>      #<Standard-Class STANDARD-OBJECT {56753B5}>
>      #<Slot-Class PCL::SLOT-OBJECT {567545D}> #<Built-In-Class INSTANCE {567BDDD}>
>      #<Built-In-Class T {567B68D}>)

> `

### (CLASS-DIRECT-SUPERCLASSES class) -> list of classes

[This is called `(CLOS::CLASS-DIRECT-SUPERCLASSES` class) in CLISP.]

[This is called `(PCL:CLASS-DIRECT-SUPERCLASSES` class) in CMU.]

As in (CMUCL):

> `

>     * (pcl:class-direct-superclasses (find-class 'teacher))

>     (#<Standard-Class PERSON {9010ADD}>)

> `

### (CLASS-DIRECT-SUBCLASSES class) -> list of classes

[This isn't available in CLISP.]

[This is called `(PCL:CLASS-DIRECT-SUBCLASSES` class) in CMU.]

As in:

> `

>     * (pcl:class-direct-subclasses (find-class 'teacher))

>     (#<Standard-Class MATHS-TEACHER {9040E9D}>)

> `