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How to use `class-direct-superclasses` and `class-precedence-list` in Steel Bank Common Lisp (SBCL)?

In tutorials such as this one, one can simply use:

CL-USER> (class-precedence-list (find-class (class-name (class-of 123))))

In LispWorks they're available via your default package-use-list, in Allegro they're exported from ACLMOP.

But, how to use class-precedence-listand class-direct-superclasses in SBCL?

Obs.: There is a new version of this tutorial on CLOS via the The Common Lisp Cookbook.

Solution

  • In SBCL, it is necessary to use package notation importing the symbol from sb-mop:

    CL-USER> (sb-mop:class-direct-superclasses (find-class (class-name (class-of 123))))
(#<BUILT-IN-CLASS COMMON-LISP:INTEGER>)

CL-USER> (sb-mop:class-precedence-list (find-class (class-name (class-of 123))))
(#<BUILT-IN-CLASS COMMON-LISP:FIXNUM> #<BUILT-IN-CLASS COMMON-LISP:INTEGER>
 #<BUILT-IN-CLASS COMMON-LISP:RATIONAL> #<BUILT-IN-CLASS COMMON-LISP:REAL>
 #<BUILT-IN-CLASS COMMON-LISP:NUMBER> #<SB-PCL:SYSTEM-CLASS COMMON-LISP:T>)