This works :
class Foo
class @_Bar
@narf = ''
@point : ->
@narf = 'what'
class @_Baz extends @_Bar
@point : ->
@narf = 'woo'
super()
This does not
class Foo
class @_Bar
@narf = ''
@point = ->
@narf = 'what'
class @_Baz extends @_Bar
@point = ->
@narf = 'woo'
super()
running Foo._Baz.point() will throw and error.
Please someone explain what is going on here.
It seems like a bug in the compiler to me. Writing
class X
@classMethod: ->
and
class X
@classMethod = ->
should be equivalent, yet super compiles differently across the two methods. In the first, it compiles correctly:
X.__super__.constructor.classMethod.apply(this, arguments);
In the second, it compiles as if classMethod were an instance method:
X.__super__.classMethod.apply(this, arguments);
This works:
class Foo
class @_Bar
@narf = ''
point : ->
@narf = 'what'
class @_Baz extends @_Bar
@point = ->
@narf = 'woo'
super()
alert Foo._Baz.point() # 'what'
alert new Foo._Bar().point() # 'what'
That is, the compiled @point= super ends up pointing to the instance point:. Its JS is: _Baz.__super__.point.call(this), which is _Bar.prototype.point.call(this). (extends defines: child.__super__ = parent.prototype).
It's clear from past Coffeescript changes that @point: is the intended syntax for static (class) methods (and used that way in the compiler itself).
point : -> attaches as Foo.prototype.point so the static method does not access it.
point : -> attaches as Foo._Bar.prototype.point.Foo._Bar.prototype.point is the place it attaches, but your answer " That is, the @point= super points to point: " is still wrong because prototype is not static, its instance.Foo._Bar.prototype.point is undefined. Mine works because that 'instance' method is defined. The crossover between static to instance is not what you intended, but that is, in effect, what the Javascript code does.There are a couple of fixes now on github. https://github.com/jashkenas/coffee-script/issues/3232
Currently the node tree for a @foo= method is different from that of a @foo: method. Because of that, a node created with = is never passed to the Class addParameters method, and is never flagged as static.
One solution, which will probably be accepted, makes sure both forms produce the same node tree.
The one I contributed https://github.com/jashkenas/coffee-script/issues/3232#issuecomment-28316501
adds a method to nodes.coffee class Class. This method is a stripped down version of addParameters, and specifically checks a = node tree.
If you need a fix in your own Coffee compiler, modify your src/coffee-script/nodes.coffee file, compile it, and put the resulting node.js in the lib directory (or use the cake build).
looksStatic can be added to the 1.6.3 nodes.coffee. I haven't played with the part involving METHOD_DEF which addresses a different issue.
supersupport to static methods (some 2 years ago).