RE: [TCLCORE] TIP #144: Argument Expansion Syntax

[John O. <ou...@el...>]

I have only been skimming the discussion on this topic, but here are
a couple of quick comments:

- First, I think the overall idea of extending the language syntax to
  allow substitutions that generate multiple arguments is very
interesting.
  This will make it much easier to program certain constructs.

- I don't think there is a "clean" syntactic way to do this without huge
  backward compatibility issues.  To me, both {} and ' are a bit ugly,
  but the feature seems useful enough to implement in spite of the
  syntactic clumsiness (either way we go, Tcl gets slightly closer
  to Perl in wartiness).  Arguments over which approach is cleaner
  don't seem very compelling to me.

- Personally, I think {} makes more sense than ' because it's completely
  backward-compatible, and because it can be extended with additional
  stuff inside the braces (e.g., {1}$x could mean take the first list 
  element of $x).  The ' notation could probably be extended also, but
  I suspect that the extensions would be syntactically clumsier.

- I suspect that this is one of the last opportunities to extend the
  language syntax, since it's based on a syntactic construct that is
  currently illegal, and there aren't very many of those.  Thus, if you
  haven't already done so, I'd suggest thinking about how this might
  evolve (what goes inside the {}) to make sure that we aren't making
  decisions that we will regret later.  For example, {}... is a special
  case of the general construct {...}..., so it should correspond to the
  most important/common/general case.

-John-