MathGroup Archive 1997

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Re: Symbols, names, objects

  • To: mathgroup at
  • Subject: [mg6557] Re: [mg6515] Symbols, names, objects
  • From: Richard Finley <trfin at>
  • Date: Tue, 1 Apr 1997 19:00:55 -0500 (EST)
  • Sender: owner-wri-mathgroup at

The problem, if I understand correctly what you are trying to do, is that
you are not differentiating between the string "x" and a variable x.  The
string "x" is just that, a string, and cannot be assigned a value whereas
the variable x, which superficially appears to be related to "x" and in fact
looks the same in output form in Mma, are actually totally different
animals.  You therefore will have to define your operator in terms of true
variables and not strings.

At 02:43 AM 3/27/97 -0500, you wrote:
>I need a function, let's call it Store, that takes two strings as
>arguments -- the NAMES of two variables the second ov which variables
>currently has some value -- and that causes the value in that variable
>to be assigned to the symbol.  (I don't care what the result returned
>by the function is; Null will do just fine.)  For example:
>    temp = {1, 2, 3};
>    Store["x", "temp"]
>After evaluating those expressions, the list {1,2,3} of numbers would
>be assigned to the variable x.
>I tried the "obvious" thing:
>   Store[newvar_String, datavar_String] :=
>       (newvar<>"="<>datavar; Null)
>but that does not work.  I've tried various alternatives, such as
>inserting "Evaluate@"<> just before datavar in the above definition,
>but that doesn't do it, either.
>More generally, I'd like Store to be able to accept as second argument
>the string representation of any expression, where such expression,
>when evaluated, give the value to be assigned to newvar.
>Evidently I'm having a lot of trouble juggling symbols, names of
>symbols, values, etc., in Mathematica (3.0).
>Can you help me?
>  Murray Eisenberg                       Internet:  murray at
>  Mathematics & Statistics Dept.            Voice:  413-545-2859 (W)
>  University of Massachusetts                       413-549-1020 (H)
>  Amherst, MA 01003                           Fax:  413-545-1801

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