Sagittarius Users' Reference

(clos user) -CLOS user APIs

User level CLOS API collection library.

Macro define-class name supers slots . options

Name must be symbol or identifier.

Supers must be list of class.

Slots must be following structure:

_slots_ ::= (_slot_ ...)
_slot_  ::= (_slot-name_ _specifiers_*)
_specifiers_ ::= `:init-keyword` _keyword_ 
              | `:init-value` _value_
              | `:init-form` _form_
              | `:reader` _reader-function_
              | `:writer` _writer-function_

Defines a new class.

Slot specifiers:

:init-keyword

This keyword specifies initialisation keyword argument used by the make procedure. Following code describes how to use:

(make <a-class> :slot-a 'slot-a-value)

<a-class> has a slot which slot definition contains the keyword :init-keyword with the keyword :slot-a. The code initialises an instance of the slot with given value slot-a-value.

:init-value

This keyword specifies an initial value of target slot.

:init-form

Similar with :init-keyword but this keyword takes expression which will be evaluated at initialiation time.

:reader

This keyword creates a procedure takes 1 argument an instance of the class to access the slot, so users can read the slot without using slot-ref procedure.

:writer

This keyword creates a procedure takes 2 argument an instance of the class and object to set the slot value with given object, so users can set the slot without using slot-set! procedure.

opttions can specify the metaclass of this class with keyword :metaclass.

NOTE: Current implementation does not support :allocation keyword by default. If you need it, see (sagittarius mop allocation).

Macro define-generic name :key class

Name must be symbol.

Creates a new generic function.

By specifying class keyword argument, users can customize the behaviour of the method specialization.

We provide <predicate-specializable-generic> for memq, memv, member and predicate specializer.

Macro define-method name specifiers body ...

Name must be symbol.

Specifiers must be following structure:

_specifiers_ ::= (_spec_ ... _rest_)
_spec_ ::= (_argument-name_ _class_) 
       | (_argument-name_)
       | (_argument-name_ (_specializer_ value))
_rest_ ::= '() | symbol
_specializer_ ::= `eq` | `eql` | `equal` | `eq?` | `eqv?` | `equal?`

Adds defined method to name generic. If the generic does not exist, this will create a new generic function implicitly.

Function slot-ref obj slot-name

Returns the slot value specified slot-name.

Function slot-set! obj slot-name value

Sets the slot value value with specified slot-name.

Function slot-bound? obj slot-name

Returns #t if the slot value specified slot-name is bounded, otherwise #f.

Generic make class args ...

Creates a new instance of class

Function is-a? object class

Returns #t if object is an instance of class, otherwise #f.

Function subtype? class1 class2