Overloading "and"

Overloading "and"

[Mike Linnig]

Here's something that I thought was illegal.  

We've all seen Ada programs that overloaded the standard operators
("+","-","*","/"). We've also seen people overload the concatination
operator "&".  But I didn't think it was possible to overload the
"AND" and "OR" operators.  

The following compiles without error on DEC Ada:

     PACKAGE test is

       function "and"(l,r: integer) return integer;

     END test;
     ----------------------------------------------------------------------
     WITH test; USE test;

     PROCEDURE mytest IS

     a, b,c : integer;

     BEGIN
       a := b AND c;		-- a call to the function TEST."AND" 
     END mytest;
     ----------------------------------------------------------------------

Many thanks to Renzo Bianchi and Gary Smith of TI, Colorado Springs for
bringing this to my attention.

Live and learn.

	-- Mike Linnig, 
	   Texas Instruments

Re: Overloading "and"

[stt]

It is illegal to overload "and then" and "or else" (as these
are "operations" but not "operators"), but it is
perfectly legal to overload the logical operators "and,"
"or," and "xor."

The only restriction about overloading operators has to
do with "=" and "/=."  You may not separately overload "/=,"
and you may only define "=" for limited types, or by renaming
another "=."   Thanks to generics, you can in fact
define "=" for any type by doing so in an instantiation
of a generic passing the type as the actual matching a formal
limited private type.