PATCH: 3.1.5-pws-6 + assorted: Doc for local parameter scope

["Bart Schaefer" <schaefer@xxxxxxxxxxxxxxxx>]

The doc currently says:

  ... `unset' can be used to delete a parameter while it is still in scope;
  this will reveal the next outer parameter of the same name.

This is not the case and hasn't been for some while.  Try:

zsh% function scope() { x=y; local x=z; unset x; echo $+x }
zsh% scope
0

There's also a bug in the caveats for special parameters; they don't merely
"remain special when unset."  They can't be made local at all.

Happily, "tied" parameters created by "typeset -T" appear to deal properly
with scoping:

zsh% tied() { foo=(x y z); local foo; foo=ABC; echo $FOO ; FOO=1:2:3 }
zsh% typeset -T FOO foo ; tied ; echo $foo
x:y:z
1 2 3

Note that assigning to the local foo did not change the global FOO, but
that assigning to the global FOO _did_ change the global foo.  This opens
up some very interesting possibilities for stupid zsh tricks.

Index: Doc/Zsh/params.yo
===================================================================
--- params.yo	1998/12/16 10:00:53	1.5
+++ params.yo	1999/02/05 06:11:56
@@ -40,7 +40,8 @@
 (Parameters are dynamically scoped.)  The tt(typeset) builtin, and its
 alternative forms tt(declare), tt(integer), tt(local) and tt(readonly)
 (but not tt(export)), can be used to declare a parameter as being local
-to the innermost scope.
+to the innermost scope.  Note that em(special) parameters cannot be made
+local.
 
 When a parameter is read or assigned to, the
 innermost existing parameter of that name is used.  (That is, the
@@ -49,9 +50,8 @@
 causes it to be created in the em(outer)most scope.
 
 Local parameters disappear when their scope ends.
-tt(unset) can be used to delete a parameter while it is still in scope; this
-will reveal the next outer parameter of the same name.  However, em(special)
-parameters are still special when unset.
+tt(unset) can be used to delete a parameter while it is still in scope;
+any outer parameter of the same name remains hidden.
 texinode(Array Parameters)(Positional Parameters)(Local Parameters)(Parameters)
 sect(Array Parameters)
 The value of an array parameter may be assigned by writing:

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