WebFund 2013F Lecture 6

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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