Re: Should undefined behavior be encouraged in Emacs?

[Stephen J. Turnbull]

Andreas Röhler writes:

 > OK, but when on that side-way, I'm afraid of forms specialising the 
 > special case, remove  specialising the special case by special condition 
 > again and so on.

That's the Emacs way, for better or worse.  You'll note that even with
100 smilies Stefan found it necessary to take the suggestion seriously
enough to veto it.

 > see all the active-region stuff for a basic example at a basic level.

UI is *never* basic.  This is especially true of Emacsen, where the
user has full access to the internals of UI.  This means that APIs
used to construct UI take decades to rationalize if you respect
backward compatibility at all.

"Active regions" is also a hard-to-interpret example for historical
reasons.  AIUI, Richard philosophically disagrees with the whole idea
of active regions, but they were a feature greatly desired by a large
fraction of users.  So they were introduced piecemeal, as options, and
were not allowed to disturb existing APIs.