PATCH: pass name ($0) and zmult ($1) to user-defined widgets

PATCH: pass name ($0) and zmult ($1) to user-defined widgets

[Bart Schaefer]

User-defined widgets should be able to change their behavior or repeat
their action when given a digit-argument.  They also ought to have a
usable $0 when FUNCTION_ARGZERO is set; I chose to pass the widget name,
so if you bind the same function to different widgets you can test for
$0 to tweak the behavior.

Index: Doc/Zsh/zle.yo
===================================================================
--- zle.yo	1998/06/01 17:08:43	1.1.1.1
+++ zle.yo	1998/06/12 08:33:25
@@ -102,6 +102,9 @@
 User-defined widgets, being implemented as shell functions,
 can execute any normal shell command.  They can also run other widgets
 (whether built-in or user-defined) using the tt(zle) builtin command.
+When tt(FUNCTION_ARGZERO) is set, they are passed their widget name
+(not their function name) as tt($0), and if tt(digit-argument) was
+used to enter a number prefix, that prefix is passed as tt($1).
 Finally, they can examine and edit the ZLE buffer being edited by
 reading and setting the special parameters described below.
 
Index: Src/Zle/zle_main.c
===================================================================
--- zle_main.c	1998/06/01 17:08:46	1.1.1.1
+++ zle_main.c	1998/06/12 08:25:14
@@ -591,10 +591,23 @@
 	    zsfree(msg);
 	    feep();
 	} else {
+	  char *name = 0, num[16];
+	  LinkList args;
 	  startparamscope();
 	  makezleparams();
-	  doshfunc(l, NULL, 0, 1);
+	  PERMALLOC {
+	    name = ztrdup(func->nam);
+	    args = newlinklist();
+	    addlinknode(args, name);
+	    if (zmod.flags & MOD_MULT) {
+	      sprintf(num, "%d", zmult);
+	      addlinknode(args, num);
+	    }
+	  } LASTALLOC;
+	  doshfunc(l, args, 0, 1);
 	  endparamscope();
+	  freelinklist(args, (FreeFunc) NULL);
+	  zsfree(name);
 	  lastcmd = 0;
 	}
     }

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Re: PATCH: pass name ($0) and zmult ($1) to user-defined widgets

[Zefram]

Bart Schaefer wrote:
>User-defined widgets should be able to change their behavior or repeat
>their action when given a digit-argument.

Yes.  But that should not be done via positional parameters.  I have
deliberately avoided passing arguments in positional parameters, so
that one widget can reliably call another without having to fiddle with
the parameters.  The numeric prefix should go into a special parameter,
or be accessible by some other mechanism.

>                                           They also ought to have a
>usable $0 when FUNCTION_ARGZERO is set; I chose to pass the widget name,
>so if you bind the same function to different widgets you can test for
>$0 to tweak the behavior.

That's a good idea.

-zefram

Re: PATCH: pass name ($0) and zmult ($1) to user-defined widgets

[Bart Schaefer]

On Jun 12, 10:37am, Zefram wrote:
} Subject: Re: PATCH: pass name ($0) and zmult ($1) to user-defined widgets
}
} Bart Schaefer wrote:
} >User-defined widgets should be able to change their behavior or repeat
} >their action when given a digit-argument.
} 
} Yes.  But that should not be done via positional parameters.  I have
} deliberately avoided passing arguments in positional parameters, so
} that one widget can reliably call another without having to fiddle with
} the parameters.

It seems useful to me to follow the Emacs model where the digit-argument
is an optional parameter to the function.

Further, I think the "have one widget call another" model in zsh is a bit
bent as it is.  Your plan is to have all widgets, built-in or otherwise,
be on equal footing; I think that should mean that they're all callable
as shell functions, and we should do away with "zle widget-name".  It's
much easer to "fiddle with the parameters" than it is to save and restore
a bunch of shared variables.

"zle widget-name" could be replaced by "execute-named-command widget-name"
if every widget acted like a shell function.

As another example, right now it's completely impossible for a user-defined
widget to initiate a history search; "zle history-search-backward" just
causes the shell to prompt the user for input, but the widget may already
have a string it wants to search for.  "history-search-backward string" is
the natural way to perform that action.

Where the shared variables are useful is for persistent state; the history
list and current position in it, the editor buffer itself and the position
of the cursor and mark(s), etc.

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com