Re: Unusual "use" semantics

[kolender@ics.uci.edu (Kurt Olender)]

Fred Hosch writes:

   My Ada compiler complains about the relation on the fourth line of the
   following

	   with TEXT_IO;
	   procedure TEST is
	   begin
	       if TEXT_IO.COL = 1 then
		   TEXT_IO.PUT_LINE ("COL is 1");
	       else
		   TEXT_IO.PUT_LINE ("COL is not 1");
	       end if;
	   end TEST;

   reporting: no operator visible for positive_count "=" universal integer.

There is one other solution that hasn't been put forward that avoids both the
"ugliness" of calling text_io."="(...) and the "use" clause, a rename
statement, as follows:

     function "=" (a, b: text_io.positive_count)
	      return boolean
	      renames text_io."=";


You may then write

    if (text_io.col = 1) ...

and the compiler will have a visible comparison operator for positive count.

I prefer this method, even though it involves more typing, because it
explicitly makes visible only those things you really need to be visible, and
reduces the potential name clashes that "use" can cause.