[vial-devel] darcs patch: normal mode commands, cc, c<motion>, s, S, -, +, J, X

[Alessandro Piras]

On 10/23/06, Brad Beveridge <brad.beveridge at gmail.com> wrote:
>
> I've just had a quick read of the patch, here are some comments:
> delete-previous-char: if you look at the primitive DELETE-CHARS
> function, there is an option to delete to the left or the right of the
> cursor.
>
> It looks like we do a lot of moving the cursor by one line, lets make
> a new function to advance/retreat by a line and put it in cursor.lisp.
> See this Emacs reference page for ideas for function names
>
> http://www.cse.huji.ac.il/support/emacs/elisp-help/elisp-manref/elisp_30.html#SEC478
>
> I don't like reusing other commands inside commands, ie in
> change-region.  What we should do is create a DELETE-REGION function,
> and have command-d-motion and change-region call that.  Same for
> subst-char, I'd rather use the primitive (DELETE-CHARS), we may want
> to change/remove COMMAND-X later.
>
> Really good, probably I'm going to have to become more disiplined in
> how I code now though :)  I can easily see myself writing exactly what
> you did :)
>
> If you want to send another patch (don't bother unrecording, just add
> to it) feel free, otherwise I'll make the changes when I roll it in.
>
> Cheers
> Brad
>
> On 23/10/06, Brad Beveridge <brad.beveridge at gmail.com> wrote:
> > On 23/10/06, laynor at gmail.com < laynor at gmail.com> wrote:
> > > Mon Oct 23 17:59:36 CEST 2006  laynor at gmail.com
> > >   * normal mode commands, cc, c<motion>, s, S, -, +, J, X
> > >   Added some normal mode commands:
> > >   "cc": change the active line
> > >   "c<motion>": change the region defined by <motion>
> > >   "s": subst char, deletes a character like "x" and then goes to
> insert mode
> > >   "S": subst line, same as "cc"
> > >   "-": goto previous line beginning, moves the cursor to previous line
> at the 1st column
> > >   "+": goto next line beginning, moves the cursor to the next line at
> the 1st column
> > >   "X": deletes previous char (like backspace in insert mode, but it
> works in normal mode)
> > >   "J": Joins the active line and the next line, It deserves to be
> fixed, because the undo is
> > >        broken (it popups the debugger when the command has no effect
> (when applied on the last line))
> > >
> > >   ---- Strange Behaviors (with respect to vim) ----
> > >   "c<motion>"   doesnt behave the same as vim, just try it in gvim and
> in vial, it's faster than
> > >                 trying to explain it here. In particular, "cj" doesnt
> open a new line after deleting,
> > >                 and cw eats the backspace that separates words.
> > >   ---- Broken behavior ----
> > >   join-lines-command ("J") breaks the undo. To reproduce this
> behavior, just go to the last line of a file
> > >   and press J, and then undo.
> >
> > Nice!  I'll look at it tonight after work and roll it in.  I think
> > I'll start a couple of new files:
> > vim-differences.txt - a list of differences to Vim
> > known-bugs.txt    - known bugs in Vial
> >
> > Thanks a lot for the patch!
> >
> > Cheers
> > Brad
> >
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>
I think that reusing commands inside other commands is ugly too, I'm
correcting some of those ugly things now.
I did it to avoid code repetition though.
I also noticed that there are some patterns in the commands code that we
could try to avoid, i.e:
(defun command-function (args) body) (define-pattern ...#' command-function
...)
This one could be better expressed with a macro that outputs those two
forms, maybe something like

(define-command command-function (args)
   (body)
   (<arguments for define-pattern, without the #'command-function))

also we could then specialize this macro, to avoid the pattern
(defun command-function2 (args)
  (active-register-needs-updating)
  body)

reducing our lines of code even more, and getting rid of some patterns.
I also thought of decoupling a little the commands from the actual bindings,
defining a bunch of variables that contain the actual bindings, like
*join-lines-command-binding*, and bound them using a macro like
(define-bindings
  (*join-lines-command-binding* "J")
  (*change-single-line-from-active-binding* "cc")
  .....)
This would make changing actual bindings clearer I think. Also I think that
surely there's a better way to do something like this
than "defining a bunch of variables", but I'm a noob and now i thought
of it as a simple method =)

We also have a bunch of commands that go into insert-mode, thus creating the
pattern
(defun foo (args)
   body
   (enter-insert-mode))
so.... what about erasing this pattern too?

Let me know what do you think!
__
Alessandro
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