Re: Help with Check Function Arguments & Options

*To*: mathgroup at smc.vnet.net*Subject*: [mg87289] Re: Help with Check Function Arguments & Options*From*: "David Park" <djmpark at comcast.net>*Date*: Sun, 6 Apr 2008 06:46:03 -0400 (EDT)*References*: <ft7gkq$bve$1@smc.vnet.net>

Andrew, Assuming you are using Mathematica Version 6, you could write your function something like the following: f::usage = "f[x,y,option] will peform an operation on x and y depending on the option."; fOperation::usage = "fOperation \[Rule] Plus is an option for f that gives the operation for combining the two arguments."; Options[f] = {fOperation -> Plus}; SyntaxInformation[ f] = {"ArgumentsPattern" -> {_, _, OptionsPattern[]}}; f[x_, y_, OptionsPattern[]] := Module[{op}, op = OptionValue[fOperation]; op[x, y] ] Then if the user types f[a] the input appears with a little red caret that indicates more arguments are needed. If evaluated with the wrong number of arguments it just returns unevaluated. If the user uses an incorrect option such as f[a,b,PlotRange->5] then PlotRange will show in red, evaluate with the default option value, and give a warning message. f[a, b] a + b f[a, b, fOperation -> Times] a b f[a, b, fOperation -> (#1^2 + #2 &)] a^2 + b -- David Park djmpark at comcast.net http://home.comcast.net/~djmpark/ "Andrew Beveridge" <acbev at lanl.gov> wrote in message news:ft7gkq$bve$1 at smc.vnet.net... >I would like to thank everyone who has previously responded to my > posts. Your advice has helped greatly. > > I have a couple of final questions. > > I am writing a package file and would like to do some argument and > option checking if possible; that is check the number of arguments > and see if there are unknown options. > > If my function has no options I think I can do this. > > f[x_,y_] := x + y > f[args___] := If[Length[{args}] != 2, Message[f::"argrx", f, > Length[{args}], 2]; Return[$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 lanl.gov > >