WebFund 2013F Lecture 6

Audio for the lecture given on September 25, 2013 is available here.

Readings

• Chapter 4, "Functions", in Learning Node

Topics

• function invocation patterns
  • method
  • function
  • constructor
  • apply
• scoping, environments

Notes

September 25

• functions
• this
  • object you are currently accessing inside of an object
• 4 method invocation patterns
  • (only difference is how this is used)
  • method
    • obj.method(args);
      • this === obj;
  • function
    • m = obj.method;
      • m(args);
  • constructor
    • x = new m(args);
      • this === { }; //empty object
      • // don't say new? it becomes the global object
    • 2 ways to keep yourself out of trouble using "new"
      • any function / constructor that is supposed to use "new" start it with a capital letter
        • don't use new at all
          • start with an empty object and return it
  • apply

x = m.apply( this value, arg array);
x = f(1) //x is a reference to h because we return it
//pointer into h along with the context in which it was called
var f = function (a) {
  var g = function (b) {
     return b+3
  }
  var h = function (c){
      return(a+g(c);
  }
  return h;
}
a = private
b= private, argument scoped to function
c = private, argument scoped to function
f = global
g = private, g&h can see each other
h = private, g&h can see each other
x = global, reference to h but cannot access g because have not returned it's value

• if you say obj.h =x will give you access to g, then f becomes a function
• assignment
  • no constructor because no use of "new"

app.configure(function(){
  app.set('views', __dirname + '/views');
  app.set('view engine', 'jade');
  app.use(express.bodyParser());
  app.use(express.methodOverride());
  app.use(app.router);
  app.use(express.static(__dirname + '/public'));
});

• using method
• app is being cast as 'views'... and set
• this in this case has been assigned to app
• node never blocks
• symbol can refer to a function