[comp.text.tex] \if !#1! to test if #1 is empty

eao@shape.mps.ohio-state.edu (Ed Overman) (06/05/90)

I suppose I am somewhat of a worrier but especially in (1) there is a real
possibility of problems since you can only use one character after the \if
statement.  (In (2) you can always do
    \def\addperiod#1{\ADDPERIOD#1!^!.!^!.!^!\END}
and the characters !^! are VERY unlikely to ever appear together.
I am thinking of using control characters (for example, ^A) instead.
Do you think this is a good or bad idea or I am really just a worrier?
(Control characters are visible in editors like emacs so there is no
real worry that a ^A might be in the text by accident but be invisible.
I have had this "invisible" bug before and it is HORRIBLE to debug.  It
happens that there can be a -0. as well as a +0. on a Sun and in FORTRAN
atan2(-0.,-1.) = -\pi  while  atan2(+0.,-1.) = +\pi !  However when printed
out -0. looks the same as +0.!)
                                        Thanks, Ed Overman