Re: Extension Language for a Text Editor

On Thu, 9 Oct 2003 05:06:32 +0900
Nikolai Weibull <[e-mail]> wrote:

> OK.  So I'm going to write a text editor for my masters' thesis.  The
> general idea of it is fixed but the extension language has not been
> settled on, yet.
<snip>

The thing with lisp, though, is that everyone has used lisp already,
and while I love lisp, there wouldn't be much of a reason to switch
from XEmacs and its twenty million extensions.

> Anyway, what I'm getting at is:
> 
> Do you figure Ruby to be a good extension language for a text
> editor?

YES.  I've been wanting "erubs" (Editor for Ruby Scripts ;-) for
awhile; something like emacs, but s/lisp/ruby.  Same design otherwise.

> * What would be easier to do using Ruby?

Well, the main thing is that ruby has a lot of very convenient pattern
and text matching functionality, and a boatload of extensions.  And
it's a very easy language, so anyone can pick it up and start
extending the editor, unlike emacs, where fewer brave the waters.

For instance, I recently wrote a bit of code to align things:

a = b            ___\         a   = b
foo = bar           /         foo = bar

This was a few simple lines of ruby.  Not counting comments, it's 44
lines of lisp that don't quite work perfectly.

> * LISP?

As much as I love lisp, I can't really think of things that would be
easier to in any of the above scheme flavors that wouldn't be easier
in ruby.

> * What language allows the most of the editing commands to be written in
>   the given language?

Ruby certainly allows this.  It's extremely trivial to extend and use
Ruby in C.  They go hand-in-hand.  Plus there are existing GUI
packages you could interface to if you wanted to provide UI handling
in ruby without a lot of work.

> * Is Ruby good enough for the task at the moment, performance wise?
> * Resource wise?  Does anyone have any statistics on this?

This is a decent benchmark:

   http://www.bagley.org/~doug/shootout/craps.shtml

Is ruby at the top of that list?  No.  (Note that most of the
languages above it are compiled, including the bigloo scheme
implementation).  But XEmacs elisp falls near the bottom, and I use
that for editing tasks daily.  Tcl and Rep both fall below.

So, I wouldn't worry about performance.  And, memory-wise, I can't
really offer benchmarks, but I have a system managing tens of
thousands of objects that doesn't present a problem.

> I'm not talking about the ease of implementing a web browser in the
> target language, rather the ease of structuring an extensible framework
> in it.

Then Ruby is ideal.  Extending and embedding it is extremely easy.
It's a really great scripting framework, even though many people
including myself use it for entire applications.

> Also, is there any way of redefining the // operator for constructing
> regular expression objects?  I'm planning on implementing a new regex
> syntax for the editor (to make searches/substitutions easier to
> describe).

No, but I would encourage you leave the existing regular expression
format intact, as, while somewhat write-only, is familiar to most
people who will be using your editor.  Redefining // would break a lot
of extension code, and alienate a large part of your audience.

However, that's not to say you can't make your own matching format.
I'm not sure what you have in mind, but there are a number of ways to
bend the syntax to integrate such things.

> thanks in advance,

If you write a ruby editor... thank _you_. ;-)

hth,

-- 
Ryan Pavlik <[e-mail]>

"You'd be surprised what a platoon of heartless ninja lawyers
 can do in favor of a position." - 8BT