Printing ggproto objects: print.ggproto

Mix.install([
  {:giggly, path: Path.join(__DIR__, "..")},
  {:kino, "~> 0.19"}
  ])

About this notebook

This notebook follows the examples on ggplot2's reference page for print(<ggproto>), which covers format(<ggproto>) too, in the order the page gives them. Each example shows ggplot2's code first and then Giggly's. An example Giggly cannot draw yet keeps its ggplot2 code and names what it is waiting for, so the page is also a list of what remains.

Printing a ggproto object calls the object's own print method if it has one. Otherwise it lists the object's members, its own and those it inherits: in one flat list by default, or, with flat = FALSE, level by level up the inheritance. format() returns that listing as text. Not in Giggly yet: ggproto(), so there are no ggproto objects to print.

An object with a print method

Dog <- ggproto(
  print = function(self, n) {
    cat("Woof!\n")
  }
 )
Dog

Printing Dog calls its own print method, which writes Woof!. Not in Giggly yet: ggproto().

Formatting an object as text

cat(format(Dog), "\n")

format() does not call the object's print method: it describes the object, listing its members, and cat() writes that text. Not in Giggly yet: ggproto().