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MathGroup Archive 2007

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Re: Returning a local array

  • To: mathgroup at smc.vnet.net
  • Subject: [mg84197] Re: Returning a local array
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Thu, 13 Dec 2007 05:50:34 -0500 (EST)
  • Organization: Uni Leipzig
  • References: <fjqj9l$6l9$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de

Hi,

but using rules for a long list of parameters
is the way that Mathematica use in all of it's
functions.
If you would like to reference a global variable,
you should pass it to the function with a Hold* attribute,
i.e,

SetAttributes[f,HoldFirst]

f[g_]:=(g["a"]=1;g["b"]=2)


Regards
   Jens

Art wrote:
> I would like to return a local array. The below seems like the wrong
> way to do it:
> 
> f[] := Module[{h}, h["a"] = 1; h["b"] = 2; h];
> g = f[];
> 
> I would like g not to be associated with the local variable h, but
> equivalent to defining it as follows:
> 
> g["a"] = 1; g["b"] = 2;
> 
> Is it better to work with rules instead? It can become awkward and I
> would like to avoid it.
> 
> f[] := Module[{h}, h={"a" -> 1, "b" -> 2}; h];
> g = f[];
> "a" /. g
> 
> The specific problem is I am reading the header for a binary file that
> has 20 or so parameters describing the binary file. I thought this
> would be the analog of a structure in other languages and a good way
> to put these parameters in a variable.
> 
> Thanks.
> 


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