Julia: High Performance Programming

Reflection capabilities

We saw in this chapter that the code in Julia is represented by expressions that are data structures of type Expr. The structure of a program and its types can therefore be explored programmatically just like any other data. This means that a running program can dynamically discover its own properties, which is called reflection. We already have encountered many of these functions before:

• typeof and subtypes to query the type hierarchy (refer to Chapter 6, More on Types, Methods, and Modules)
• methods(f) to see all the methods of a function f (refer to Chapter 3, Functions)
• names and types: given a type Person:

  type Person
      name:: String
      height::Float64
  end

  Then, names(Person) returns the field names as symbols: 2-element Array{Symbol,1}: ...