Re: RCS, again: another removed functionality: undo last-checkin

[Dmitry Gutov <dgutov@yandex.ru>]

On 10/01/2015 04:07 PM, Eli Zaretskii wrote:

> No.  Existing features might make no sense if (a) they didn't make
> sense when introduced (it happens!),

You mean features that were useless or broken from the start?

> or (b) if the reason for their
> existence is no longer valid, like a program that is no longer
> available, or operation that is impossible with today's platforms, or
> so clearly unused that there's no doubt it could be still useful to
> anyone.

...or became irreparably broken over time. That's a pretty high standard 
to consider a feature for removal.

When I said "doesn't make sense", I meant sense in the context of the VC 
framework. Which supposedly has some internal logic, ergonomics, etc.

> Breaking backward compatibility is about the worst crime package
> maintainers could commit, in my opinion.  (I know it's not shared by
> many of the others.)

This general opinion (and you're not alone holding it) is one of the 
most tedious parts of the Emacs ecosystem, IME. It's not that I *love* 
removing features, but being unable to do that at all makes the burden 
of a maintainer harder when making changes or adding new features.

> It makes veteran users of a package feel like
> second-class citizens whose needs and workflows can be disregarded all
> too easily.

Removing features is always a tradeoff. While no one wants to make old 
users sad, if their needs would still be achievable at the cost of 
workflow changes, we should be able to make that sacrifice.

At some point in the future (distant, in all likelihood, so this is just 
a rough example), I imagine that would mean sacrificing support for 
antique VC backends entirely, in favor of simpler VC implementation, or 
better support of the newer backends. There's nothing stopping the 
veterans from adopting modern VCSes, you know.