Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!haven!adm!cmcl2!lanl!jlg
From: jlg@lanl.gov (Jim Giles)
Newsgroups: comp.lang.misc
Subject: Re: language commenting constructs
Message-ID: <10581@lanl.gov>
Date: 17 Mar 89 01:40:13 GMT
References: <7555@killer.Dallas.TX.US>
Organization: Los Alamos National Laboratory
Lines: 47

From article <7555@killer.Dallas.TX.US>, by elg@killer.Dallas.TX.US (Eric Green):
> in article <10460@lanl.gov>, jlg@lanl.gov (Jim Giles) says:
>> do otherwise.  The comment syntax which requires explicit termination
>> of comments _IS_ more difficult to learn to use safely.  The safe
>> [...] 
> In a recent program, I have code similiar to the following: */
> 
> /* table */
> int Transitions[NUMSTATE][NUMCLASS] = {
> /*  statenum   digit  number delimiter quote EOF EOL ... */
> /* 0 */          2,     5,     8,       15,   10, 19,
> /* 2 */          4,     19,   ....
> 
> [...]          When I do assembler or Lisp I regularly run into
> situations where I want to imbed a comment into a statement for
> clarity's sake, and can't do it.

Please read my original comment again.  I only oppose a comment syntax
which _requires_ explicit termination.  I don't oppose a comment syntax
which _allows_ explicit termination so long as the end of record also
terminates the comment.  My favorite syntax for what you have above
would go something like this:

!  table
int Transitions[NUMSTATE][NUMCLASS] = {
!  statenum   digit  number delimiter quote EOF EOL ...
!   0      !!   2,     5,     8,       15,   10, 19,
!   2      !!   4,     19,   ....
!   5      !!   ....
! ....

Here the comments begin with ! and end with !! or the end of line.  This
syntax even allows code (that doesn't include !!) to be 'commented out':

      a = b+c
!     x = a*(z+y)            ! trailing comment
      for ( ...) ...

Here the second statement was commented out.  The extra exclamation point
doesn't effect the fact that the comment ends at the end of line.  As I
say, this only works on lines that don't contain an explicitly termionated
comment.  But, since I prefer ifdef for removing code, this doesn't
matter much.  This can't be done with C, of course, since ! is an operator
in C.  But the C++ syntax ('//') might be extended (terminate comments
with '\\' maybe).

J. Giles