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Re: arguments/realtime3d

  • To: mathgroup at
  • Subject: [mg32286] Re: [mg32246] arguments/realtime3d
  • From: "P.J. Hinton" <paulh at>
  • Date: Fri, 11 Jan 2002 04:35:20 -0500 (EST)
  • Organization: "Wolfram Research, Inc."
  • Sender: owner-wri-mathgroup at

On Wed, 9 Jan 2002, daniel wrote:

> Is there a way to obtain the number of arguments with wich
> the function was called as in
> f[x___?OptionQ]:=Module ...?

In principle, it should be possible to invoke Length[] on a list wrapped
around the argument sequence.

In[1]:= g[x___?OptionQ] := Print["Number of arguments: ", Length[{x}]]

In[2]:= g[a -> b, c -> d, e -> f]
Number of arguments: 3

Why would one create a function with only optional arguments in the first
place?  Do you intend a Null argument to be valid input as well?

> I  would like to check if x contains only valid options of f (defined with
> Options[f,a->1])

See the function FilterOptions[], which is defined in the Standard Package
Utilities`FilterOptions`.  For more information, paste the following
expression in a notebook and evaluate it.

  FrontEnd`HelpBrowserLookup["AddOns", "Utilities`FilterOptions`"]

> second question: is there a way to have RealTime3D under Linux (Matematica
> 4.0)

No, RealTime3D wasn't introduced on X Window front ends until the release
of Mathematica 4.1.

P.J. Hinton
User Interface Programmer                         paulh at
Wolfram Research, Inc.
Disclaimer: Opinions expressed herein are those of the author alone.

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