Meet the new pdxrlang organizers!

• Sophie Yang

• Marley Buchman

• Ted Laderas

• John Smith

S3 objects

R's first and simplest OO (Object Oriented) system

In Adv. R book

S3 is informal and ad hoc, but it has a certain elegance in its minimalism: you can’t take away any part of it and still have a useful OO system

S3 - when to use S3 generics/methods

• inputs can have many different classes

• you want to do different things with different classes

• you want something that's light weight

• you want to build on top of a base R generic (e.g, plot)

S3 - beware!

• consider S3 failure behavior - see .default

• parameters should be consistent across S3 methods

• pay attention to whether methods on generics are exported in your pkg

• as a user: don't call S3 methods directly, call the generic

• no validation of checking of contents

• extended generic methods of base functions from diff. pkgs can conflict!

• S3 classes can be easily dropped/lost (next slide)

further reading

• nick tierney's paper/blog post

• Adv. R chapter on objects