CODEWITHSUNDEEP
coffeescript
Jamie Curtis
Jamie Curtis

Reputation: 916

Why can't I call this function?

This is getting ridiculous...

Why do I get an error when I try to do this?

#...codecodecode...

g = generateGuid()

#...codecodecode...

generateGuid = ->
  "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx".replace /[xy]/g, (c) ->
    r = Math.random() * 16 | 0
    v = (if c is "x" then r else (r & 0x3 | 0x8))
    v.toString 16

All I want to do is call a private function...

Upvotes: 2

Views: 361

Answers (2)

Trevor Burnham
Trevor Burnham

Reputation: 77426

driis is correct. To expand on his answer: You may be used to the JavaScript idiom

function generateGuid() { ... }

which allows you to call generateGuid from anywhere within its scope (even before its definition). CoffeeScript doesn't do this; instead, it compiles to

var generateGuid = function() { ... }

There are several reasons for doing this, but the long and short of it is that functions obey the same scoping rules as all other variables. Before a value has been assigned to generateGuid, generateGuid() is an attempt to call undefined.

Note that, due to the way asynchronous callbacks work in JavaScript, this will work:

setTimeout (->
  g = generateGuid
  # ...codecodecode...
), 0

generateGuid = -> ...

Upvotes: 5

driis
driis

Reputation: 164341

You are trying to call the function before it's defined. This works:

#...codecodecode...

#...codecodecode...

generateGuid = ->
  "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx".replace /[xy]/g, (c) ->
    r = Math.random() * 16 | 0
    v = (if c is "x" then r else (r & 0x3 | 0x8))
    v.toString 16

g = generateGuid()

In case this is surprising to you, remember that Coffeescript compiles to Javascript - in fact, it is not much more than syntactic sugar over some Javascript. Most of the rules that apply in Javascript will also hold true in Coffeescript.

Upvotes: 3

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