set-macro-character, get-macro-character

set-macro-character, get-macro-character Function

Syntax:

get-macro-character char &optional readtable → function, non-terminating-p

set-macro-character char new-function &optional non-terminating-p readtable → t

Arguments and Values:

char—a character .

non-terminating-p—a generalized boolean. The default is false.

set-macro-character, get-macro-character

readtable—a readtable designator . The default is the current readtable.

function—nil, or a designator for a function of two arguments.

new-function—a function designator .

Description:

get-macro-character returns as its primary value, function, the reader macro function associated with char in readtable (if any), or else nil if char is not a macro character in readtable. The secondary value, non-terminating-p, is true if char is a non-terminating macro character ; otherwise, it is false.

set-macro-character causes char to be a macro character associated with the reader macro function new-function (or the designator for new-function) in readtable. If non-terminating-p is true, char becomes a non-terminating macro character ; otherwise it becomes a terminating macro character .

Examples:

(get-macro-character #\\{) → NIL, *false* 
		     (not (get-macro-character #\;)) → false 
		     The following is a possible definition for the *single-quote reader macro* in *standard syntax* : 
		     (defun single-quote-reader (stream char) 
		       (declare (ignore char)) 
		       (list ’quote (read stream t nil t))) → SINGLE-QUOTE-READER 
		     (set-macro-character #\’ #’single-quote-reader) → T 
		     Here single-quote-reader reads an *object* following the *single-quote* and returns a *list* of **quote** and that *object*. The *char* argument is ignored. 
		     The following is a possible definition for the *semicolon reader macro* in *standard syntax* : 
		     (defun semicolon-reader (stream char) 
		       (declare (ignore char)) 
		       ;; First swallow the rest of the current input line. 
		       ;; End-of-file is acceptable for terminating the comment. 
		       (do () ((char= (read-char stream nil #\Newline t) #\Newline))) 
		       ;; Return zero values. 
		       (values)) → SEMICOLON-READER 
		     (set-macro-character #\; #’semicolon-reader) → T 

Side Effects:

The readtable is modified.

See Also:

*readtable*

Expanded Reference: set-macro-character, get-macro-character

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(set-macro-character, get-macro-character )