Re: [TCLCORE] TIP #293: Argument Expansion with Leading {*}

[Michael A. C. <mi...@cl...>]

On 11/2/06, Will Duquette <wi...@wj...> wrote:
>
> On Nov 2, 2006, at 5:25 PM, Robert Hicks wrote:
>
> > Neil Madden wrote:
> >> Still digesting this, but one point leaps out at me:
> >> ...
> >>>     2. The usage of both *{expand}* and *{}* will be deprecated.
> >>>        However, both idioms will remain enabled as alternatives.
> >> ...
> >>
> >> What does "remain enabled" mean in relation to {}? Does this TIP also
> >> enable {} as expansion syntax in the 8.5+ line?
> >>
> >
> > Oh yes, why would you do that? There should only be one idiom for
> > expand. You shouldn't leave alternatives in as that is just asking for
> > abuse.
>
> ActiveTcl 8.5 (though not, IIRC, the core Tcl builds) supports {} as
> an alternate syntax for {expand}.  I remember Jeff Hobbs talking about
> it at the conference in '05.

Jeff did talk about it at the conference.  {} in lieu of {expand} is
principally ActiveTcl or a customized build only, not the stock Tcl
distribution.  The code for {} support is in the 8.5 core but it is
#ifdef'ed out by default.  (You'd have to define ALLOW_EMPTY_EXPAND to
get it.)

> I believe the notion was (Warning! I might be making this up!) that
> we might eventually have several syntax escapes of the form
> {expand} or {this} or {that} or {<your word here>}, but that
> {expand} was likely to always be the most common, therefore if
> the word were left out, as in {}, it would be reasonable to let
> it default to {expand}.
>
> Me, I like {*} better.

Ditto, many times over! :-)

Michael