Re: How to change definition of gnus-summary-exit?

[Emanuel Berg <embe8573@student.uu.se>]

Nikolaus Rath <Nikolaus@rath.org> writes:

> What's an advice (in this context)?

An advice can be a lot of things, in the Emacs
context, but in the context of your issue, I suspect
the person who gave the piece of advice to use an
advice, he suspected that you want something to always
happen say, before or after the invocation of the
regular function.

This can be done with advices. Here is an example that
I use, which isn't complicated to figure out what
it does:

    (advice-add 'gnus-summary-insert-old-articles :after
                (lambda (dummy) (gnus-apply-kill-file)))

Typically, advices are used when you don't want any
major and complicated changes to a function. (But
there are many thing that can be done with them.)

However, just because they can be done doesn't mean
that is the best way, and always so. Indeed, sometimes
it is better to redefine the function as you did.

However, in my experience the *best* way to do it is
to write a brand new function - use the existing code
if need be, but do everything new - that way, no
collisions, the help is intact, etc. But the best
advantage to this method is security. Because say you
invoke function F at situation S. It doesn't do
exactly what you want. So you change F and all is well
- *at S*! But often F is used in other situations, and
even by other software which you are unaware of.
So instead, copy and edit F into F', and at S, change
the keybinding that previously invoked F, so that it
now invokes F'!

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http://user.it.uu.se/~embe8573