worked examples from Genolini's A (Not So) Short Introduction to S4 (2008)
http://christophe.genolini.free.fr/webTutorial/notSoShort.php
- minimize execution errors
- minimize type errors
- execute validity checking
- support inheritance
- encapsulate the object and its tools
setClass(Class, representation, prototype, contains=character(), validity, access, where, version, sealed, package, S3methods = FALSE, slots)
setMethod(f, signature=character(), definition, where = topenv(parent.frame()), valueClass = NULL, sealed = FALSE)
setGeneric(name, def= , group=list(), valueClass=character(), where= , package= , signature= , useAsDefault= , genericFunction= , simpleInheritanceOnly = )
Added travis-ci to test how it works with r-unit