MathGroup Archive 1997

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Re: Attributes

  • To: mathgroup at smc.vnet.net
  • Subject: [mg6449] Re: Attributes
  • From: Dick Zacher <dick at loc3.tandem.com>
  • Date: Fri, 21 Mar 1997 22:59:49 -0500 (EST)
  • Organization: Tandem Computers
  • Sender: owner-wri-mathgroup at wolfram.com

Marlies Brinksma wrote:

> > When removing the attribute Orderless of the function Times
> > (ClearAttributes[Times, Orderless]), this attribute disappears (which is
> > its normal behaviour;-), but reappears(!) after a function-call of a funtion I
> > defined. I checked this function thouroughly, but I cannot find any relation
> > to Times.
> 
> I performed some tests and now I know that the feature I described is due to
> the function TableForm. So probably this function has some kind of a side
> effect related to Times? Does anyone know more about this?

Interesting.  The attributes only got restored the first time I invoked
TableForm.  So If I invoke TableForm first, then clear the attribute,
then invoke TableForm more times, the attributes stay cleared.  I'm
curious as to what is happening, even though I don't think I would
choose to write code that depends on clearing the Orderless attribute of
Times.

That is not to say that I wouldn't ever change the attributes of
built-in functions. I used to routinely change the HoldAll attribute of
If to HoldRest in version 2.2; in version 3.0 one doesn't have to do
that any more!
-- 
-----------------------------
Dick Zacher                    
Performance Engineering Dept., Tandem Computers
zacher_dick at tandem.com     phone: 408-285-5746     fax:   408-285-7079


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