您如何正确使用Java进行OOP并明确指定变量范围？

Question

In Introduction to Object-Oriented JavaScript , a formal description is given on how to use javascript in an object oriented fashion. Your code for functions inside objects would like along the lines of:

$(function() {
  var oPerson = new cPerson("Florian");
  alert("Hi! My name is " + oPerson.sMyNameIs());
});

function cPerson(sSetName)
{
  var sName= sSetName;
  var oPersonInst = this;

  this.sMyNameIs = function () {
    return sName;
  };
}

With a bit more experience, you probably want a more clearcut reference to the instantiated class, so you modify the class code as such (and I add another function too):

function cPerson(sSetName)
{
  var sName= sSetName;
  var oPersonInst = this;

  this.sMyNameIs = function () {
    return oPersonInst.sName;
  };

  this.sMyFullNameIs = function () {
    return oPersonInst.sMyNameIs();
  };
}

Now we have come accross three different ways of referring to function or variables from within class functions:

return sName;
return this.sName;
return oPersonInst.sName;

Suppose I want to call the sName variable in the instantiated class very specifically, and these example functions will get more and more and even more complex and in depth as development goes on.

I think that the first option ('return sName;') is uncertain, as you are not quite sure whether you are referring to the variable in the right targeted instantiated class scope. It could be an accidental local var that you are calling.

The second, using this , IMHO, is also not perfect as this apparently changes depending on situations, and you can't (?) rely on that you are calling the right variable in the instantiated class specifically.

So the third reference, is IMHO, the best looking reference. Very specifically defined right at instantiation of the class. How can there be any doubt that the var sName of the class is meant.

Q1 : Why are functions in the class defined with this. ? Can it not better be defined with oPersonInst.something = function () { //... }; ?

Q2 : why does, in code that I have given, alert(oPersonInst.sMyNameIs()); work, but alert(oPersonInst.sName); does not (at least, not within $.each( something, function() { //right here }) ), but alert(sName); DOES work (not favored IMHO, because of the above mentioned reasons)?

Q3 : Can someone pot some exemplary code, or maybe even change this sample code, where solid out-of-local-scope references are used, that will work outside as well as inside $.each(...) callback functions (or other callback related functions) ?

Forgive my confusion, we're all learners, and I feel a hole in my brain. This article did not explain my concerns over this very well.

Answer 1

this doesn't change randomly at all.. it always means the current closure (function):

• if you are in function_1() -- this means function_1
  
• if you are in function_1>function_2 -- function_2 is the current closure and this means function_2

IF you need function_1's this in function_2 you have to capture it while in function_1:
meaning var function1This = this;

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and the way to reference a var by using the functions name before it means static access. It has different semantics

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so use this.var to be sure you get the INSTANCE's variable
use a 'captured this pointer' to access your parents INSTANCE's variable

and only use name.var if you want to get the static, shared (between all instances) value