Re: propose adding Icicles to Emacs

[Richard Stallman]

    > I'm not sure why the redefinition within Icicle mode is a no-no.  I'm not
    > arguing, but I don't see the reason for the prohibition.

    It's OK for an external package (tho I prefer defadvice), but for reasons of
    maintainability and general principle it's not good inside Emacs.
    We probably do have such things already inside Emacs, but we want to reduce
    such occurrences rather than increase them.

The reason is this.  To have a definition of foo in file A
and another in file B can be confusing.  A person who sees
the main definition in A won't know there is another.
(It's the same consequence if B advises foo.)

It is much better to have one single definition of foo, in file A,
with a conditional or hook to take care of what B wants.