0.21_prototypal.js

// lets us use one useful object and then make more
var myMammal = {
name : 'Herb the Mammal',
get_name : function ( ) {
return this.name;
},
says : function ( ) {
return this.saying || '';
}
};
// console.log(myMammal);


var myCat = Object.create(myMammal);
myCat.name = 'Henrietta';
myCat.saying = 'meow';
myCat.purr = function (n) {
var i, s = '';
for (i = 0; i < n; i += 1) {
if (s) {
s += '-';
}
s += 'r';
}
return s;
};
myCat.get_name = function ( ) {
return this.says( ) + ' ' + this.name + ' ' + this.says( );
};
// console.log(myCat);
// ---------------------------------------
// This is differential inheritance. 
// By customizing a new object, we specify the differences 
// from the object on which it is based.

var block = function ( ) {
// Remember the current scope. Make a new scope that
// includes everything from the current one.
var oldScope = scope;
scope = Object.create(scope);
// Advance past the left curly brace.
advance('{');
// Parse using the new scope.
parse(scope);
// Advance past the right curly brace and discard the
// new scope, restoring the old one.
advance('}');
scope = oldScope;
};

// Items defined in a scope are not visible outside of the scope.
// In a sense, an inner scope inherits from its outer scope.