Re: semantics of ?=

[Gabor Greif <address@hidden>]

Bruce Hoult wrote:
> 
> At 1:13 AM -0400 17/9/02, P T Withington wrote:
> >On Sunday, Sep 15, 2002, at 20:00 US/Eastern, Bruce Hoult wrote:
> >
> >>I believe that use of ?=it in awhile() should refer to a variable of
> >>that name in the textual environment in which awhile is mentioned.
> >
> >I.e., as if awhile were expanded without hygiene for 'it', just like
> >C would do.
> >
> >I was not party to the #dylan conversation, so perhaps I am missing
> >something; but I agree with Bruce.
> 
> The guts of it (but hopefully better thought-out) is what you see on
> the newsgroup/info-dylan.
> 
> Unfortunately, both gd and fd currently behave identically in
> thinking that "it" is unbound in intermediate-level macros such as
> pig-out unless you use ?=it there too.  "it" is available at the root
> (non macro) level without ?=.  Which I think is pretty useless and

What do you mean by "being available"?

"?=" used in a macro definition simply says:
Inject or look up this identifier in(to) the expansion scope instead of
the macros definition scope.

> possibly dangerous.  This may well be correct according to the spec,

Sorry but I cannot see where this could be dangerous. If in definition context
there is a binding "it", than that will be used. Just like \element etc.

	Gabor



> but if so I don't think it's a *useful* spec -- or a necessaru one.
> 
> -- Bruce