Topics.md

REPL

• why useful to know the different "moving" parts
• Parsing
• Partially complete commands
• Syntax errors

Evaluate

• literal values
• finding/resolving symbols - pi
  • variables and assignment
  • environments and global environment
  • search path
• function calls
• everything is a function call
• details of function calls
  • Matching arguments to parameters
  • Scope within a function
    • environments/call frames
    • package environments
  • Lazy evaluation
  • pass by value ("everything" is a copy)
  • return value
    • last value in a { }
    • applies to if()
      • x = if(cond) {...} else {...}
• finding symbols in a package.

Debugging

• Proactive and reactive.
• debug(), browser()
• options(error = recover),
• call stack
  • sys.calls()
  • sys.frames()
  • sys.frame()
• try()/tryCatch()
• options(warn = {0, 1, 2})

Writing Functions

• default values
• idioms for making functions more flexible, reusable, different entry points.
• on.exit()
• warning() and stop().
• closures and scope
  • <<- - non-local assignment

Formulae

• evaluation
• environment
• weights in modeling. Boosting.

Everything is an object.

• class() - how do we think of it.
• typeof() - how is it built
• str()
• names()
• length()
• dim()

Attributes

• attr()
• structure(obj, attr = , attr = ...)

Data Types

• Hierarchy of vector types
• NA
• subsetting - 6 types.

OOP - S3, S4 methods

• Key concept
  • same function name/verb (e.g. plot, summary), customized behavior based on type.
  • extensiblity
  • Inheritance
• Method lookup - S3, S4
• Inheritance mechanism - NextMethod(), callNextMethod()