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Re: what is Global`Class?

  • To: mathgroup at
  • Subject: [mg20358] Re: [mg20354] what is Global`Class?
  • From: "Andrzej Kozlowski" <andrzej at>
  • Date: Sun, 17 Oct 1999 02:45:35 -0400
  • Sender: owner-wri-mathgroup at

There is no global Class symbol. Roman Maeder's Classes.m package  
originally appeared in the Mathematica Journal. An updated version of this
package was included with R. Maeder's book "Mathematica Programmer II" and
also with the second edition of John W. Gray's "Mastering Mathematica". Both
of these books are based on version 3 of Mathematica.  However, I believe
that this particular package did not actually need any updating from version
2. I believe that the version on MathSource is exactly the same.

I have tried this package just a few minutes ago and it seems to work (with
Mathematica 4) without apparent problems. There are no warning messages and
no name clashes.

I believe that your problem is probably caused by incorrect way of loading
the package. Try it again in  a fresh Mathematica session. Did you use Needs
or Get (<<)? How exactly did you do it?

>From: Joe Strout <joe at>
>To: mathgroup at
>Subject: [mg20358] [mg20354] what is Global`Class?
>Date: Sat, 16 Oct 1999 00:47:42 -0400

> When I try to load the Classes module (from MathSource and written for
> Mathematica 2.2) into Mathematica 4, I get the following warning:
> Class::"shdw": "Symbol \!\(\"Class\"\) appears in multiple contexts \
> \!\({\"Classes`\", \"Global`\"}\); definitions in context
> \!\(\"Classes`\"\) \
> may shadow or be shadowed by other definitions."
> (Ugh, please excuse the ugly markup tags; I haven't figured out how to
> avoid them ("Copy as Plain Text" doesn't do it, despite what it
> claims)).
> Anyway, it's saying there's a Global`Class symbol, and sure enough,
> this shadows the one defined in classes: "Context[Class]" returns
> "Global`".
> What is this global Class symbol?  It's not in the master index, and it
> doesn't seem to have a ::usage.
> Finally, is this the right module to be using for object-oriented
> programming in Mathematica?  If so, why hasn't it been updated since
> v2.2, especially when it generates warnings and has inconvenient name
> clashes?
> Thanks,
> -- Joe
> --
> ,------------------------------------------------------------------.
> |    Joseph J. Strout           Biocomputing -- The Salk Institute |
> |    joe at                 |
> `------------------------------------------------------------------'
> Check out the Mac Web Directory!

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