Re: global variables & data tags (a la X-Windows callbacks)

[Lars Arvestad <arve@nada.kth.se>]

RB> Are there any plans to add a "tag" argument to gh_new_procedureX_Y() /
RB> gh_new_procedure() / scm_make_gsubr() ?

RB> The motivation is, as was designed in X-Windows, to pass a "data tag"
RB> which can be passed to the procedure (a "callback" in X-Windows jargon).
RB> This mechanism allows me to avoid the use of global variables -- the
RB> relevant data can be passed along to the procedure.

I don't understand what you would need this for. In X, this is used
since you don't have closures in C which you basically need for
callbacks. 

In Scheme on the other hand this is easy to do by wrapping a function
in a let-form. Since you are defining new Scheme procedures, you are
not limited to use C, right?

Could you explain the possible applications?
	
	Lars

-- 
Lars Arvestad               Dept. of Numerical Analysis and Computing Science
                       Royal Institute of Technology (KTH), Stockholm, Sweden