Parallel Computing for Data Science

B.6. THE R LIST TYPE 303

So now we have two objects of a class we’ve chosen to name ”employee”.

Note the quotation marks.

We can write class generic functions:

> print . employee <− function ( wrkr ) {

+ cat ( wrkr$name , ”\n” )

+ cat ( ” s a l a r y ” , wrkr$ s al a ry , ”\n” )

+ cat ( ” union member” , wrkr$union , ”\n” )

+ }

> print ( j )

Joe

s a l a r y 55000

union member TRUE

> j

Joe

s a l a r y 55000

union member TRUE

What just happened? Well, print() in R is a generic function, meaning

that it is just a placeholder for a function specific to a given class. When we

printed j above, the R interpreter searched for a function print.employee(),

which we had