code/extfmts.lisp

;;; domain.

;;; 

(ext:file-comment

 "$Header: /Volumes/share2/src/cmucl/cvs2git/cvsroot/src/code/extfmts.lisp,v 1.35.4.5 2010/09/06 01:01:27 rtoy Exp $")

 "$Header: /Volumes/share2/src/cmucl/cvs2git/cvsroot/src/code/extfmts.lisp,v 1.35.4.6 2010/09/06 15:35:28 rtoy Exp $")

;;;

;;; **********************************************************************

;;;

;;; DEF-EF-MACRO  -- Public

;;;

;;; Create an ef-macro (external-format macro).  This creates a

;;; function named Name that will process an external format in the

;;; desired way.

;;;

;;; Paul Foley says:

;;;   All the existing ef-macros are provided with the implementation,

;;;   so they all use lisp::lisp as the id; it's intended for people

;;;   who want to write their own macros~there are some number of

;;;   slots (+ef-max+) used by the implementation; the idea is that

;;;   you can write something like (def-ef-macro foo (ef my-tag 4 1)

;;;   ...) to implement 1 of a total of 4 new macros in your own

;;;   "namespace", without having to know how many are implemented by

;;;   others (e.g., the 10 used by the base implementation...which

;;;   could change with the next release -- and if several libraries

;;;   each add their own, the total number, and the position of each

;;;   one's slots within that total, may change depending on load

;;;   order, etc.)  When you write the above, it allocates 4 new

;;;   places and associates the base index with "my-tag", then the

;;;   "idx" value is relative to that base.  The id lisp:lisp always

;;;   has its base at 0, so it doesn't need to go through ensure-cache

;;;   to find that out.

(defmacro def-ef-macro (name (ef id reqd idx) body)

  (let* ((tmp1 (gensym))

	 (tmp2 (gensym))