(setf (macro-function symbol &optional environment) new-function)
symbol—a symbol.
environment—an environment object.
function—a macro function or nil
.
new-function—a macro function.
Determines whether symbol has a function definition as a macro in the specified environment.
If so, the macro expansion function, a function of two arguments,
is returned. If symbol has no function definition
in the lexical environment environment, or its definition
is not a macro, macro-function
returns nil
.
It is possible for both macro-function
and
special-operator-p
to return true of symbol. The macro definition must
be available for use by programs that understand only the standard
Common Lisp special forms.
(defmacro macfun (x) '(macro-function 'macfun)) → MACFUN (not (macro-function 'macfun)) → false
(macrolet ((foo (&environment env)
(if (macro-function 'bar env)
''yes
''no)))
(list (foo)
(macrolet ((bar () :beep))
(foo))))
→ (NO YES)
(setf macro-function)
, defmacro
, and macrolet
.
The consequences are undefined if environment is non-nil
in a use of setf
of macro-function
.
defmacro, Section 3.1 (Evaluation)
setf
can be used with macro-function
to install
a macro as a symbol's global function definition:
(setf (macro-function symbol) fn)
The value installed must be a function that accepts two arguments, the entire macro call and an environment, and computes the expansion for that call. Performing this operation causes symbol to have only that macro definition as its global function definition; any previous definition, whether as a macro or as a function, is lost.