Override order is reversed when providing functions instead of Objects

[kafoso]

In test.js, exports.testOverride verifies that the "youngest" Object (or "class") overrides the same-name function of its parent (or "base"). This test of course works.

However, if the prop argument is a function, the override order is reversed. See example below.

exports.testOverrideOfFunctions = function(test) {
    test.expect(2);
    var A = inherit(function(){
      this.method = function() {
          return 'A';
      };
    });
    var B = inherit(A, function(){
      this.method = function() {
          return 'B';
      };
    });

    test.equal(new A().method(), 'A');
    test.equal(new B().method(), 'B');
    test.done();
};

The above test fails. See output below.

✖ testOverrideOfFunctions

AssertionError: 'B' == 'A'
    at Object.equal (/usr/local/lib/node_modules/nodeunit/lib/types.js:83:39)
    at Object.exports.testOverrideOfFunctions (/home/kafoso/git/inherit/test/test.js:142:10)
    at Object.<anonymous> (/usr/local/lib/node_modules/nodeunit/lib/core.js:236:16)
    at /usr/local/lib/node_modules/nodeunit/lib/core.js:236:16
    at Object.exports.runTest (/usr/local/lib/node_modules/nodeunit/lib/core.js:70:9)
    at /usr/local/lib/node_modules/nodeunit/lib/core.js:118:25
    at /usr/local/lib/node_modules/nodeunit/deps/async.js:513:13
    at iterate (/usr/local/lib/node_modules/nodeunit/deps/async.js:123:13)
    at /usr/local/lib/node_modules/nodeunit/deps/async.js:134:25
    at /usr/local/lib/node_modules/nodeunit/deps/async.js:515:17

Naturally, the prop argument should be an Object per your documentation. However, it would be a nice addition.

[dfilatov]

What's the case you need to pass Function instead of Object?

[kafoso]

@dfilatov
To allow for private variables (or "scope-only" variables) inside the functions. Example:

exports.testInheritedFunctionsWithPrivateVariables = function(test) {
    test.expect(2);
    var A = inherit(function(){
      var _privateVariable = 1;
      this.method = function() {
          return _privateVariable+2;
      };
    });
    var B = inherit(A, function(){
      var _privateVariable = 9;
      this.method = function() {
          return _privateVariable+2;
      };
    });

    test.equal(new A().method(), 3); // Works
    test.equal(new B().method(), 11); // Throws up
    test.done();
};

Output:

✖ testInheritedFunctionsWithPrivateVariables

AssertionError: 3 == 11
    at Object.equal (/usr/local/lib/node_modules/nodeunit/lib/types.js:83:39)
    at Object.exports.testInheritedFunctionsWithPrivateVariables (/home/kafoso/git/inherit/test/test.js:145:10)
    at Object.<anonymous> (/usr/local/lib/node_modules/nodeunit/lib/core.js:236:16)
    at /usr/local/lib/node_modules/nodeunit/lib/core.js:236:16
    at Object.exports.runTest (/usr/local/lib/node_modules/nodeunit/lib/core.js:70:9)
    at /usr/local/lib/node_modules/nodeunit/lib/core.js:118:25
    at /usr/local/lib/node_modules/nodeunit/deps/async.js:513:13
    at iterate (/usr/local/lib/node_modules/nodeunit/deps/async.js:123:13)
    at /usr/local/lib/node_modules/nodeunit/deps/async.js:134:25
    at /usr/local/lib/node_modules/nodeunit/deps/async.js:515:17

[qfox]

@kafoso You still can do this with __constructor property, isn't it?

exports.testInheritedFunctionsWithPrivateVariables = function(test) {
    test.expect(2);
    var A = inherit(function(){
      var _privateVariable = 1;
      this.method = function() {
          return _privateVariable+2;
      };
    });
    var B = inherit(A, { __constructor: function(){
      this.__base.apply(this, arguments);
      var _privateVariable = 9;
      this.method = function() {
          return _privateVariable+2;
      };
    }});

    test.equal(new A().method(), 3); // Works
    test.equal(new B().method(), 11); // Should also works as expected
    test.done();
};

[qfox]

@dfilatov Do we want this behaviour as a sugar?

[dfilatov]

I don't think so. I still don't understand what a sugar is.

[kafoso]

You still can do this with __constructor property, isn't it?

The variable is only available within the constructor's function scope, then. What I'm asking for is private variables, which are available in every function within the "class" Object, but inaccessible from the outside. Entirely like visibility keywords work in PHP, Java and many other high-level programming languages.