Re: SyntaxInformation Question

*To*: mathgroup at smc.vnet.net*Subject*: [mg110772] Re: SyntaxInformation Question*From*: "E. Martin-Serrano" <eMartinSerrano at telefonica.net>*Date*: Mon, 5 Jul 2010 21:13:46 -0400 (EDT)

Hi, Sorry for the previous post that looks almost unreadable on my screen probably due to problems with hidden special characters which distort the page format and others. I hope this one reads better. __________________________________________________ In the ref/SyntaxInformation in the Help the following example can be found: "f can have any number of arguments, but each should be a two-element list:" SyntaxInformation[f] = {"ArgumentsPattern" -> {{_, _} ...}}; {f[{x, y}, {a, b}], f[x, {a, b}, {x, y, z}]}; In the first part of the example: 'f[{x, y}, {a, b}]', '{x, y}' is a two-elements list, so is '{a, b}'; then syntax constrain holds and it is understandable for me. In the second part of the example: 'f[x, {a, b}, {x, y, z}]', 'x' evaluates to a list but not necessarily to a two-elements list. According to the scarce explanation given in the example, it is not excluded for 'x' to evaluate to a 12-elements list '{x, y}', however the syntax constrain allows it to pass; following with the example the list '{a, b}' is again a two-elements list, so it pass the check. But finally '{x, y, z}' is a three-elements list but it is allowed to pass the constrain too; and so do {v, x, y, z}, and {u, v, x, y, z}, and any list of whatever any other length as this {f[{x, y}, {a, b}], f[x, {a, b}, Array[100, x]]}. In the example Options[f]={aaa->1,bbb->2,ccc -> 4}; SyntaxInformation[f]={"ArgumentsPattern"->{_,_,OptionsPattern[]}}; the syntax specification allows for two parameters and a list of options to be submitted to the function 'f[]'. But it does no seem to work as expected since the following is allowed to pass (and it seems Ok since just two parameters and a list of options are submitted) f[x,y, aaa->2,bbb->3,ccc ->4]; but the following is allowed to pass too, despite, in this case, 6 parameters (plus the options) are submitted instead of just the two parameters specified in the SyntaxInformation[f] definition f[x, y, z, k, l, m, aaa->2,bbb->3,ccc->4]; I am certainly missing something important here and, clearly, I do not understand the explanation given for this very basic command. So I would appreciate any clarification from the Group. Or maybe Wolfram should provide a complete tutorial on it or a clearer explanation. Regards E. Martin-Serrano