copy-class

copy class in CoffeeScript

(which means "copy constructor in JavaScript")

installation

npm install copy-class

usage

 
class OriginalClass
    @staticProp: 123
 
    instanceMethod: ->
        return 'hello'
 
AnotherClass = require('copy-class').copy(OriginalClass, 'AnotherClass')
AnotherClass.prototype.instanceMethod = ->
    return 'another hello'
 
 
new OriginalClass().instanceMethod() # hello 
new AnotherClass().instanceMethod() # another hello 

the second argument of copy is the constructor name.

By default it is the original class name. ('OriginalClass' in this example)

when to use this???

The time when you want to add some features to already-existing class without changing the name of the class. It's very rare case, but Remember me when you want to use me.

vs extends

extends cannot set the same constructor name.

performance

tested with 10 static props and 10 instance methods (normal size):

1. class creation is 3.5 times slower than "extends"
2. instance creation is almost the same as "extends"

class creation usually is not repetitive operation, so performance is not the matter. it's much more important that no significant difference in creation of instance.

you can try benchmark by

$ cake benchmark