[plt-scheme] texpict and slideshow confusion

From: Robby Findler (robby at cs.uchicago.edu)
Date: Thu Jun 8 13:47:22 EDT 2006

You want mrpict.ss, not texpict.ss in the second require line below.
texpict defines the same structure as mrpict, but slide.ss is using
mrpict.ss's internally (and yes, the error messages should be better).


At Thu, 8 Jun 2006 18:42:03 +0100, "Paulo J. Matos" wrote:
> Hi all (again),
> Last hour was searching for an error which I just found out and it
> makes no sense.
> Check the code:
> (require (lib "class.ss")
>          (prefix tp: (lib "texpict.ss" "texpict"))
>          (prefix ss: (lib "slide.ss" "slideshow")))
> (tp:pict? (ss:blank 10 10)) ;==> #f
> (tp:cc-superimpose (ss:blank 10 10) (ss:blank 10 10)) ;==> wierd error
> The error is:
> pict-width: expects args of type <struct:pict>; given instance of a
> different <struct:pict>
> This error is terrible: first, pict-width is the function in error but
> no pict-width is on sight and one cannot delve into the internals (it
> seems backtrace stays on user-code). We know, however, due to colors
> that the problem is in cc-superimpose.
> Even so, the error is completely wierd... Kind of like: expecting a
> string, but received a string. heh
> I understand that the problem is that I'm using functions required
> from different modules but isn't it the same structure that is just
> being re-provided by slide from texpict? So, internally what's the
> problem?
> -- 
> Paulo Jorge Matos - pocm at sat inesc-id pt
> Web: http://sat.inesc-id.pt/~pocm
> Computer and Software Engineering
> INESC-ID - SAT Group
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