compute-class-potential-initargs

compute-class-potential-initargs Generic Function

Summary

Computes the valid initargs of a class.

Package

clos

Signature

compute-class-potential-initargs class => initargs

Arguments

class⇩

A class.

Values

initargs⇩

A list of symbols, or t.

Description

The generic function compute-class-potential-initargs is called to compute the initialization arguments of a class. This set of valid initargs is used by make-instance when its arguments are checked.

class is the class passed to make-instance. That is, compute-class-potential-initargs specializes on the metaclass.

initargs is either a list of valid initargs, or t meaning that any initialization argument is allowed.

There is a supplied method on t, which returns nil.

The other supplied method is on standard-class. This consults the Relevant Methods, which are the applicable methods of make-instance, allocate-instance, initialize-instance and shared-initialize. If any of the Relevant Methods have a lambda list containing &allow-other-keys then initargs is t. Otherwise initargs is a list containing:

all the &key arguments from Relevant Method lambda lists, and:
the initargs of the slots of class and its superclasses, and:
any extra initargs specified via the class option :extra-initargs (see defclass for details of this), and:
any extra initargs returned by class-extra-initargs.

The list initargs contains no duplicates, and the result of compute-class-potential-initargs is cached so that it is not recomputed unless one of the Relevant Methods, the class or its class precedence list is altered.