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Re: Help with Check Function Arguments & Options

Andrew Beveridge wrote:
> I would like to thank everyone who has previously responded to my 
> posts. Your advice has helped greatly.
> I have a couple of final questions.
> I am writing a package file and would like to do some argument and 
> option checking if possible; that is check the number of arguments 
> and see if there are unknown options.
> If my function has no options I think I can do this.
> f[x_,y_] := x + y
> f[args___] := If[Length[{args}] != 2, Message[f::"argrx", f, 
> Length[{args}], 2]; Return[$Failed]]
> This type of check has been posted to the message board before.
> My question is assume that f[x,y] has multiple options, that is
> Options[f] = {opt1 -> 1, opt2 -> True}, etc
> How do I check if the user entered the correct options?
> Thanks again for all of your help.
> Regards,
> Andrew
> Andrew C Beveridge
> MS M888
> Los Alamos National Laboratory
> Los Alamos, NM  87545
> 505-665-2092
> e-mail: acbev at
By far the best answer to this is to use the new OptionsPattern and 
OptionValue features introduced at 6.0 - look them up in the help 
system. This will separate options from other arguments and check that 
the options used are actually valid.

David Bailey

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