Hi Gerard, I once use this little trick for handling a variable number of argument:
f: func [a [integer!] b [unset! integer!]][either value? 'b [a + b][a]] >> f 1 2 == 3 >> f 1 == 1 Please remark that the type of the argument must be explicitely declared, otherwise: f: func [a b][either value? 'b [a + b][a]] >> f 5 6 == 11 >> f 8 ** Script Error: f is missing its b argument ** Near: f 8 Could this be useful to you ? gretz, ==christophe > -----Original Message----- > From: Gerard Cote [mailto:[EMAIL PROTECTED] > Sent: lundi 5 avril 2004 23:36 > To: [EMAIL PROTECTED] > Subject: [REBOL] [Function] with [Variable number of args] > > > > Hi List, > > while relaxing for a couple of days, I reread one of my old > APL books and wanted to try implement some useful mechanisms > for vector > operations (a vector being a one dimensional array) using > simple REBOL scripts. some of these mechanisms are somewhat > similar to the > higher-level functions Ladislav and other advanced REBOLers > have written in the past. I'll give you 2 simple examples below since > this is where I found some questions about the way REBOL can > or not manage functions with a variable number of arguments. > > One of the mechanisms I wanted to emulate is simply an > extension of the maths operators to take into account two > arguments that are > not only single values but that also could be a block of > values, like in the use of my ++ function : > > >>++ 1 2 > == 3 > > >>++ 1 [1 2 3 4 5] > ==[2 3 4 5 6] > > >>++ [6 7 8 9 10] 1 > ==[7 8 9 10 11] > > >>++ [1 2 3] [4 5 6] > ==[5 7 9] > > All of this works well for now. > > The problem is that I also wanted to include in the same > function another useful behaviour generally known as +/ in > APL, like in > this example : > > >>++ [1 2 3 4] ; 1 + 2 + 3 + 4 == 10 > ==10 > > But I never was able to say REBOL to use only one argument - > leaving the second one optional when necessary - and to not take into > account of the second one defined like this : > ++: function [arg1 arg2][ > ... > > Can someone tell me if there is one simple way to do this > with REBOL or if I have to define another independant > function to do this. > For now what I can do is check if the second arg is an empty > block or none but this is not as elegant as it could be. > > I must admit that I didn't begin to look for an answer by > myself yet but I will do this tonight. I found this could be > interesting > for other newbies too to know more about the subject. > > Thanks, > Gerard > > -- > To unsubscribe from this list, just send an email to > [EMAIL PROTECTED] with unsubscribe as the subject. > > -- To unsubscribe from this list, just send an email to [EMAIL PROTECTED] with unsubscribe as the subject.
