Comments on: When Is Backwards-Compatibility Not Worth It?

By: Max Kanat-Alexander

Max Kanat-Alexander — Wed, 13 Feb 2008 10:10:52 +0000

It’s most apparent in languages. For example, Larry decided to have the following code work in Perl:

$var =~ /regex/

Because of that feature, various methods of parsing Perl are difficult to impossible. You can’t know what “/” means until runtime, in some circumstances (sometimes it means division). The actual times when that happens are really small, but Perl will forever have complex code to distinguish the meaning of “/” because of that feature. That’s one where you really can’t break backwards-compatibility.

Also, you can slow forward progress to the point of a crawl, which might as well be blocking it. For example, in Perl 5, we still don’t have formal subroutine arguments after all these years, even though there are many people working on the codebase.

-Max

By: Gerv

Gerv — Wed, 13 Feb 2008 09:44:33 +0000

How do such features “block forward progress” (as opposed to, say, slow it down a bit because the code is more complex)?

By: Max Kanat-Alexander

Max Kanat-Alexander — Tue, 12 Feb 2008 19:17:03 +0000

Thanks! Yeah, I agree about the deprecated thing.

-Max

By: SerJ

SerJ — Tue, 12 Feb 2008 18:50:21 +0000

Totally agree with you on that point. It’s normal to see that kind of mentality on the Perl community, and that way of thinking is affecting the language more that it’s helping it.

I think that if you mark something as deprecated, you have to tell when that deprecated functionality is going to disappear. Maybe that’s the solution to the problem.

Once again, very well said!