Re: strange behavior in bind

From: Brian Denheyer <briand_at_deldotd.com>
Date: Tue, 9 Mar 1999 14:23:40 -0800 (PST)

>>>>> "Ben" == Ben L Di Vito <bld_at_air57.larc.nasa.gov> writes:

    Ben> I noticed some similarly strange behavior with bindings. I had tried
    Ben> a binding of the form (lambda (xx yy) ... xx yy ...). To my surprise,
    Ben> I found that when the mouse x position was, say, 123, the value for xx
    Ben> was 123123.

Yes, sounds very similar to what I am seeing.

    Ben> I later noticed in the STk manual that the binding's lambda
    Ben> arguments are supposed to be single-character variables to
    Ben> match the Tcl/Tk "%" conventions. So there must be some kind
    Ben> of textual substitution going on here rather than simple
    Ben> Scheme binding and evaluation. Is this the right
    Ben> interpretation for what the underlying implementation is
    Ben> doing? It sounds like it would explain my case and possibly
    Ben> this one:

Most certainly that is what is happening. Another undesirable
side-effect of the underlying "tcl'ness" of Tk. However, I'm fairly
sure that my code which broke was working at one time, so this effect
is recent.

You are correct in pointing out that since it is supposed to be a 1
character subsitution, it's really _my_ code which is broken, as usual
:-)

Brian
--
Brian Denheyer             briand_at_deldotd.com
Deldot Design, Inc.        (503) 788-1607
__              
\/.d = Electronic design and development
Received on Tue Mar 09 1999 - 23:25:05 CET

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