Thanks to everyone who replied to my query. It is much appreciated. Reading Hadley Wickham's book Advanced R and in particular S3 classes reveals that a class needs to be written allowing inhertinance (by passing the subclass parameter as an argument) and its methods written carefully to function properly with child class. The S3 objects in the package I am using do not appear to have been written with inheritance in mind. I will look for another (less elegant) solution.
Thanks again, Kym > On 9 Aug 2017, at 8:48 am, Hadley Wickham <h.wick...@gmail.com> wrote: > > You might find http://adv-r.hadley.nz/s3.html to be helpful (in > particular, http://adv-r.hadley.nz/s3.html#constructors-1, gives my > advice about subclass constructors) > > Hadley > > On Mon, Aug 7, 2017 at 7:06 PM, Kym Nitschke <kym.nitsc...@icloud.com> wrote: >> Hi R Users, >> >> I am relatively new to programming in R … so I apologise if my questions >> appear ‘dumb’. >> >> I am using a package that defines a number of S3 classes. I want to create >> an S3 child class of one of these classes. The parent class has a contractor >> with many arguments. I have been having difficulty writing the child class >> contractor. I have been unable to find a good reference in the internet for >> writing S3 classes. What I have been able to find out so far is that the >> child class constructor should call the parent class constructor … which in >> this case requires passing the argument list with a variable number of >> arguments (i.e. there are a number of optional arguments) from the child to >> the parent. >> >> So my first question is … is there an easy way to do this? The match.call >> function will return a call object .. however the attributes function when >> used on the call object returns a ‘NULL’. >> >> My second question is … can any one recommend a good reference for object >> oriented programming in R which includes a comprehensive discussion of the >> S3 class model? >> >> Thanks >> >> Regards, >> >> Kym >> ______________________________________________ >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. > > > > -- > http://hadley.nz ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
