Re: [ART@THINK-AQUINAS.ARPA: Another

[Guy Steele <gls@THINK-AQUINAS.ARPA>]

    Date: Tue, 18 Mar 86 16:39 EST
    From: David C. Plummer <DCP@SCRC-QUABBIN.ARPA>
	Date: Tue, 18 Mar 86 14:33:57 cst
	From: preece%ccvaxa@gswd-vms (Scott E. Preece)
	> From: David A. Moon <Moon@SCRC-STONY-BROOK.ARPA>
	>     Date: Tue, 18 Mar 1986  10:42 EST
	>     From: "Scott E. Fahlman" <Fahlman@C.CS.CMU.EDU>
	>     I'd like to see the combination #! be reserved for something more
	>     important and interesting than comment out a single expression.
	> We typically use #+IGNORE for this, although personally I'm a big fan
	> of semicolon for comments.
	----------
	So, why not use "#;", which the book says is undefined?  Seems
	reasonably mnemonic to make it "ignore s-expression" given that
    I don't think this is in the domain of the language, since there is
    already a perfectly good way (two actually: ; and #|...|#) to comment
    something out.  The responses so far have shown that several people have
    different ways to accomplish the goal....
It seems to me that if several people have independently found it necessary
to invent another way, however crocky, to comment out an s-expression,
then the existing methods are not perfectly good.  I too have found ; and
#| inconvenient for this purpose.  One reason is that one is forced not
only to insert the comment mark itself but often also one or more newlines.
	(cond ((am-i-losing) (try-to-win))
	      ((am-i-winning) #|(try-to-lose)|#)
	      (t (try-to-try)))
really looks awful, and to use ";" one must do something like
	(cond ((am-i-losing) (try-to-win))
	      ((am-i-winning)
	       ;;(try-to-lose)
	       )
	      (t (try-to-try)))
[the double semicolon being necessary to make the indentation
conventions of many editors do the right thing].  The problem with
either of these methods, however, is that both ; and #| are forced to
treat their contents as unstructured text, and therefore many editors
cannot deal with editing the code in its commented-out state (it won't
indent properly, etc.).  This is the main attraction for me of a standard
way to comment out an s-expression.  I am a bit leery of #+ignore or
#+++ignore, because some turkey could make IGNORE or ++IGNORE be a feature
after all and ruin everything; but #+(or) strikes me as an acceptable
idiom (but perhaps #-(and) is better to emphasize its negative nature).
--Guy