[Ma-linux] [Dclug] Strange Emacs Lisp behavior

[Aaron M. Ucko]

Alan McConnell <alan at patriot.net> writes:

> Oh gosh.  Will I have to retrain my fingers?  I fear so.

Only if you've been in the habit of typing control-h to erase
characters; I'm merely suggesting that you redefine what the Backspace
key sends.  (Pretty much any decent terminal application should give you
the option.  Alternatively, you can let Emacs create its own windows
rather than running it inside a terminal.)

> I think I understand this.  I know only cursorily about scoping and its
> problems.  I remember "extern" and "static" declarations from my C days.

C, like most modern(ish) languages, is lexically scoped, in that local
variable declarations hold for corresponding textual code blocks.
Dynamic scoping, by contrast, essentially amounts to establishing
temporary definitions of global variables which wind up visible to other
functiosn called from within the relevant blocks.  It occasionally comes
in handy as a means to allow for implicit parameters.

FWIW, Perl naturally offers both ;-): "my" and "our" declares lexically
scoped variables, whereas "local" declares dynamic ones.  (Its name
dates from old versions that only supported dynamic scoping, which can
be easier to implement.)

> What about guile?  Lilypond, the music-typesetting SW uses guile.

Ah, yes, that's another notable Scheme implementation, lighter-weight than
PLT Scheme and as such more suitable for embedding.  Thanks for pointing
it out.

-- 
Aaron M. Ucko, KB1CJC (amu at alum.mit.edu, ucko at debian.org)
http://www.mit.edu/~amu/ | http://stuff.mit.edu/cgi/finger/?amu@monk.mit.edu