Some weird stuff with contexts for a CoffeScript&Javascript beginner

coffee_learning1.coffee

set_name = (name) -> @name = name

set_name 'Juan'
console.log name  #Juan                                                                                            
console.log @name #undefined

#How context works here is pretty weird...
#Looks like set_name is not evaluated on "this" context
#This seems quite true if we do:

set_name.call this, 'Juan'                                                                                               console.log @name #Juan

#If we looking at the compiled Javascript:

var set_name;                                                                                      
set_name = function(name) {
  return this.name = name;
};
set_name('Juan');
console.log(name);
console.log(this.name);

#I'd say that functions have no context by default. Am I right?
#Or, maybe, the function itself is an object and has it's own context
#Need some clarification on this one

The execution context of a function (the 'this' keyword) depends only on the way you call/execute the function.
There are several ways of executing a function:
a) set_name('Juan') -> the context is the global object. What the global object is depends on the enviroment you are running. In a browser it is window, in node.js is an object called global.... You shouldn't use 'this' if you plan calling the function like this
b) set_name.call(someObject, 'Juan') -> This way 'this' is 'someObject'
c) set_name.apply(someObject, ['Juan']) -> This way 'this' is 'someObject'
d) someObject.set_name('Juan') -> This way 'this' is 'someObject'. But you need 'someObject' to have the function set_name. To do so you can just do someObject.set_name = set_name You can define too the method set_name using the constructor or its prototype

Thanks for your help @eamoderubio! It's crystal clear now :·)