Re: Refactoring and Ada

[Robert A Duff <bobduff@shell01.TheWorld.com>]

Richard Riehle <richard@adaworks.com> writes:

>...It would be a disaster, in
> the given program if a maintenance programmer were to test for less-than when
> I wanted greater-than.

The renaming trick can actually *cause* that problem:

    function "and"(X, Y: T) return T renames Mumble."and";
    function "or"(X, Y: T) return T renames Mumble."and";

Oops.  A cut-and-paste bug.

The problem is that renaming is too powerful for this purpose: renaming
allows you to change the name of the thing, which you don't want to do
9 times out of 10.  In this case, you just wanted to import the thing,
without actually renaming it.  And the reader won't notice this bug
easily, because there are thousands of lines of these boring renamings;
the reader thinks, "yeah, yeah, yeah, I already know what that says,
I need not read it carefully".

- Bob