Re: extra-interactive functions

[martin rudalics <rudalics@gmx.at>]

 > mr> `find-file' uses `switch-to-buffer' and `switch-to-buffer' should be
 > mr> avoided in Elisp code.
 >
 > The docstring for `switch-to-buffer' says not to use it to avoid
 > "messing with the window-buffer correspondences" which is good enough
 > for me (though I'm still curious what that really means).

A user might want to display that file visting buffer in a certain way
and has customized options like `special-display-buffer-names' or
`special-display-regexps' for that purpose.  If you call
`switch-to-buffer', the user cannot control the placement of the buffer
in the window or frame of her choice.

 >>> Also, if `find-file' should be avoided in ELisp generally, the docstring
 >>> should say so, like it does for many other functions.
 >
 > mr> Indeed.
 >
 > But that's tedious to do by hand.  If we tag the function symbol
 > (e.g. `switch-to-buffer') with some extra-interactive property, we can
 > tag all the functions that call it as well at compile time.  Wouldn't
 > that be nicer?  The docstring can then automatically say "unsafe to call
 > because it calls `switch-to-buffer'" which is nice and more helpful.

There are only very few interactive functions that should be allowed to
call `switch-to-buffer'.  `find-file' may fit into this category because
that's what users traditionally expect it to do (although I plan to have
it call a function `pop-to-buffer-same-window' sooner or later).  In the
distant future there should be no function calling `switch-to-buffer' at
all.

martin