Question

Here’s a code example

class person 
  constructor: (@name, @age) ->

bob = new person("bob", 11)

if person?
  alert "yes!"
else
  alert "no"

In this, I test if a person class was instantiated, and it alerts “yes!” like it’s supposed to. Because bob is a person, and was instantiated.

But over here:

class person 
  constructor: (@name, @age) ->

if person?
  alert "yes!"
else
  alert "no"

I want this to alert “no”, because no person was instantiated, and yet it still alerts “yes!”

So what is the correct way to test if a class has been instantiated.

CLARIFICATION:

I do not want to test and see what bob is. I want to see if ANY FORM OF PERSON WAS INSTANTIATED.

Answer 1

You are testing to see if the person class is defined. This will accomplish what you want.

class person 
  constructor: (@name, @age) ->
    person.prototype.instantiated = true

if person.prototype.instantiated
  alert "yes!"
else
  alert "no"