bug#8415: 23.3.50; Extensible Emacs Registers

[Leo]

On 2011-04-05 11:07 +0800, Stefan Monnier wrote:
> The end point is pretty much the same, but all the intermediate steps
> are safe and easy to check.

I think a structure still is a better approach. It offers uniformity and
allows access to the value stored in each slot so one can easily build a
new register reusing values from an old one which, in some use cases
(defadvice), can be convenient.

>> Well, there's EIEIO.  It gives you the ability to easily add methods
>> while not baking the dispatch into each one.  On the other hand, it's a
>> quite a bit of code to pull into the core at runtime.
>
> Indeed.

I have thought about using EIEIO in the beginning and ruled it out since
it is required at run time.

Leo