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- To: cl-cleanup@Sail.stanford.edu
- Subject: Issue: DEFINITION-FUNCTIONS
- From: Masinter.pa@Xerox.COM
- Date: 9 Oct 87 15:20 PDT
I promised I would submit a proposal for "named definitions" for making
documentation etc more extensible in Common Lisp. I don't have a formal
proposal, but I've been sitting on this very rough draft...
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A "definition type" a symbol, like one of the following
function (including defun, defmacro, define-modify-macro...)
Definition types are used by several functions, including DOCUMENTATION.
A defining form, such as a form introduced with DEFUN, DEFSTRUCT, or
whatever, is said to give a given definition type to a specific name.
Frequently, a definition name is a symbol, but need not be.
Given a form (such as DEFUN, DEFMACRO and the like) returns the
type of thing defined by it.
(Can be either a form or else the symbol that introduces such a
DEFSTRUCT, DEFTYPE => TYPE
DEFMACRO, DEFUN, DEFINE-MODIFY-MACRO, ... => FUNCTION
DEFSETF => SETF
DEFVAR, DEFPARAMETER, DEFCONST => VARIABLE
Given a form (no symbol allowed), returns the name of the thing
defined. Often SECOND, but e.g.
with DEFSTRUCT might do more processing.
(documentation name definition-type)
As before, type can be any definition type.
(delete-definition name definition-type)
delete all effects of name having a definition of type
(delete-definition name 'function) replaces (fmakunbound name)
(delete-definition name 'variable) replaces (makunbound name)
For adding more:
(def-definition-type type-name description &key undefiner)
Define type-name as a new kind of definition type.
Undefiner is a function which will remove a definition
(defdefiner definer-name type &key undefiner name-function)
says that definer-name defines things of type.
Undefiner says how to remove 'em
name-function, defaults to second, says, given an expression
which starts with definer-name, what the name of the thing is, e.g.,
(defdefiner defun function :undefiner #'fmakunbound :name-function
(defdefiner defstruct type :undefiner #'si:remove-structure-definition
:name-function #'(lambda (x) (if (consp (second x)) (car (second x))
Note that when you undefine a name using delete-definition, *all* of
the known undefiners
(both the general one supplied with def-define-type and the specific
for each definer with defdefiner) are applied. The undefiner should not
if there is no definition.
function is defined by (DEFINE-MODIFY-MACRO DEFMACRO DEFUN)
type is defined by DEFTYPE DEFSTRUCT
variable is defined by DEFCONSTANT DEFPARAMETER DEFVAR
setf is defined by DEFSETF and DEFINE-SETF-METHOD
define-type is defined by DEF-DEFINE-TYPE
(ed name &optional type)
Optional type allows you to say which definition if there is more than
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The following make sense in some environments:
(has-definition-p name definition-type &key)
True if name has some definition of given type
Return list of all types for which name has a definition
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With the error proposal, DEFINE-PROCEED-FUNCTION would define function,
With CLOS, DEFCLASS would define a class.
This is awkwardly said, so I may have to explain it better: definers are
for things that define the *whole thing*, for which other definitions
are mutually exclusive. Thus, a defmethod doesn't define the generic
function, it only defines a piece of the generic function. So (defmethod
frob ((a widget) ...) ...) can't be a "definer" for the function frob.
There is some design choice of whether it is a definer for the function
(:method frob widget) (since definition names need not be symbols) or
whether it is the definer for the method (frob widget). I think this
need not be nailed down by the definition protocol.
I think this is separate from the "function spec" proposal because
"function specs" have to do with identifying pieces of executable code
which might have breakpoints, etc. assigned to them.