_events is shared across subclasses

[lpstein]

Behavior broke in node 0.10, see nodejs/node-v0.x-archive#7157 (fixed in node.js master).

Example:

var A = function() {};
A.prototype = new events.EventEmitter();

var a1 = new A();
var a2 = new A();

a1.on('test', function() {
  console.log('test');
});
a2.emit('test');

This logs 'test' where it shouldn't.

[defunctzombie]

Can we get a fix and test PR for this?
On May 30, 2014 6:57 PM, "lpstein" notifications@github.com wrote:

Behavior broke in node 0.10, see nodejs/node-v0.x-archive#7157
nodejs/node-v0.x-archive#7157 fixed in node.js master
vkurchatkin/node@2956f03
.

Example:

var A = function() {};A.prototype = new events.EventEmitter();
var a1 = new A();var a2 = new A();
a1.on('test', function() {
console.log('test');});a2.emit('test');

This logs 'test' where it shouldn't.

—
Reply to this email directly or view it on GitHub
#10.

[defunctzombie]

The fix from node.js master doesn't work in ie8. So if we want to keep parity with current browsers we support the fix has to be different. Personally don't care about dropping IE8 support.

[darkyen]

Drop IE 8 ? Please ?

[leewaygroups]

@lpstein Looking at your code example, a2.emit('test'); , logging 'test' is normal.

Reason
A.prototype = new events.EventEmitter(); implies that every instance of A will share among other things same copy of events collection -- Pure case of prototypal inheritance.

Suppose you do not want this, you can make instances have their own private events collection by:
var A = function() {
events.EventEmitter.call(this);
};

Note: this does not take away the shared events collection as explained earlier, it only shadows it.

Another option is to require util module then do this:
util.inherits(A, events.EventEmitter);

Cheers!!

[patrickroberts]

You can also do something like:

function A() {
  events.EventEmitter.call(this);
}

A.prototype = Object.create(events.EventEmitter.prototype);
A.prototype.constructor = A;

That's one of the methods Babel uses to transpile ES6 inheritance when Object.setPrototypeOf doesn't exist. And it doesn't just shadow it, it doesn't even create a shared events collection since Object.create() does not invoke the constructor!

[lpstein]

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[darkyen]

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[goto-bus-stop]

Fixed in #40. Will try to release soon once I get it working on IE8 again