🚀 go-pugleaf

In article <1993Jan3.150933.3089@wam.umd.edu>, joel@wam.umd.edu (Joel M. Hoffman) writes...
>Is there any way to incorporate boolean operators into TeX's \if
>constructions?  What I'd like to do is something like
> 
>	\if\a\b \and \if\a\c \or \if\a\d
>		\dosomething
>	\else
>		\dosomethingelse
>	\fi
> 
>Any ideas?

If you don't mind some very confusing constructs:

AND:
    \ifnum 0\if\a\b \else 1\fi \if\a\c \else 1\fi=0 ...
            -------            -------  
OR: 
    \ifnum 0\if\a\b 1\fi \if\a\c 1\fi >0 ...
            -------      -------
EOR: 
    \ifnum \if\a\b -\fi \if\a\c -\fi 1<0 ...
           -------      -------

In these, the underlined parts are the tests to be ANDed or ORed.  They
end with a space after the 0.  They can be extended to combining more than
two tests at a time ( a or b or c or d ).

So for the example:  if (a=b and a=c) or a=d then

\ifnum 0% for the outer "or", the next line is the first test, the inner "and"
  \ifnum 0\if\a\b \else 1\fi \if\a\c \else 1\fi=0 % note space at end
\else 1\fi 
  \if\a\d % the second test of the OR, simply compare a and d
1\fi >0 % another trailing space

You could make macros \Land, \Lor to hide the mess, but they could not be 
skipped in conditional text unless there were equal ifs and fis visible.


Donald Arseneau        asnd@reg.triumf.ca