I'm trying to get Jasmine's setup and teardown methods to work for me.
I must be using it wrong, because I can't get variables to stay in scope after setup.
Doesn't work:
describe 'classes/model', ->
beforeEach ->
model = new Model()
describe 'the basics', ->
it 'extends Backbone.Model', ->
expect(model).toBeInstanceOf Model # Fails. 'model is not defined'
I thought maybe setup has to be in the scope of the describe. But this also doesn't work:
describe 'classes/model', ->
describe 'the basics', ->
beforeEach ->
model = new Model()
it 'extends Backbone.Model', ->
expect(model).toBeInstanceOf Model # Fails. 'model is not defined'
Works. (but doesn't use setup convenience)
describe 'classes/model', ->
describe 'the basics', ->
it 'extends Backbone.Model', ->
model = new Model()
expect(model).toBeInstanceOf Model
Am I doing something wrong that prevents beforeEach from working?
Found it. Probably should have noticed sooner :)
Have to pay attention to the way CoffeeScript manages variable scope to make this work.
describe 'classes/model', ->
model = null # get it in scope
beforeEach ->
model = new Model()
describe 'the basics', ->
it 'extends Backbone.Model', ->
expect(model).toBeInstanceOf Model
Related
I'm trying to define a helper method in konacha in coffeescript, something like this
#expect_int_is_universal = (i) ->
expect(i).to.equal 42
describe '#test', ->
it 'checks if integer is 42', ->
#expect_int_is_universal(42)
Is it possible in konacha?
edit: error log here:
update: the fix is putting it inside a beforeEach block
beforeEach ->
#expect_int_is_universal = (i) ->
expect(i).to.equal 42
describe '#test', ->
it 'checks if integer is 42', ->
#expect_int_is_universal(42)
mu is too short hasn't successfully converted his comment as the answer, but i'll provide it here below:
# (AKA this) inside your it callback is not the same # as at the top level so you're defining expect_int_is_universal as a method on one object but trying to call it as a method on another object. Try without the #s. I don't know enough Konocha, Mocha, or Chai to say any more than that
I want to join (use) classe in Coffescript files, and i found some usefull ideas here (sry for not including all links), since none fitted my needs (at least not as i like) I tried to find an own solution, this will work fine, but is there something I have overseen?
following "base" and "base class" are not OO words, I just did not find better names
I have a base (class) file TechDraw
class TechDraw
constructor: ->
$(window).load () =>
... do somthing
wave_to_me: ->
say 'I wave' # say is a basic func, I always use for debugging (console.log)
#TechDraw = new TechDraw
this works fine
Now I want to expand/extend my class with "sub classes/modules" in other files; ie. I have a TechDrawLine, and a TechDrawCalc, ans so on
What I did, was building a coffee file for each of them like:
class TechDrawConnector
constructor: (p)->
#parent=p
wave: (msg) ->
say 'yes its me, the connector:',msg
`window.TechDrawConnector = function(p) { return new TechDrawConnector(p) };`
# the last instead of a simple new like
# #TechDrawConnector = new TechDrawConnector
and my base(ic) class/module I extendet like this:
class TechDraw
constructor: ->
$(window).load () =>
#Connector=window.TechDrawConnector(this)
#LineGuy=window.TechDrawLineGuy(this)
#Connector.wave('init')
Since I am a newbee in coffeescript (yes javascript also) my solution feels to simple ...
Have I overseen somthing? The Polution of the global namespace is not so bad I think
You cant create an "extension" that way.
If you define the same class in the same namespace a second time the first class will simply be overwritten and become in accessible. This will mostly be dependent on the order of loading of the compiled JavaScript files.
However you could either later add an method to the prototype of the class
#file a.coffee
class A
constructor: ->
#foo()
#file B.coffee
A::foo = -> #do something
However this is no good style and can certainly be very confusing some time and lead to brittle errors.
Better would be to use a form of dependency injection
#file a.coffee
class A
constructor: (#closure) ->
$(window).load () => #closure()
#file B.coffee
new A () ->
#Connector=window.TechDrawConnector(#)
#LineGuy=window.TechDrawLineGuy(#)
#Connector.wave('init')
I have a class Child which extends Test. I want to call a function from Test from Child.
I tried this:
class Test
constructor: ->
#i = 'hello world'
f1: -> console.log #i
f2: -> console.log 'hello'
class Child extends Test
run: ->
Test::f1()
hello = new Child()
hello.run()
When I call hello.run(), it calls Test.f1(), but the result is undefined. It's not setting the static variable #i before it's running Test.f1().
If I switch Test::f1() to Test::f2(), it gives me the correct result.
I need to know how should I make Test's constructor run when I create a new Child() so that #i is defined in Test when I run Test::f1() from Child.run().
Thanks! :D
Here's one way of doing it:
class Test
#i: 'hello world'
#f1: -> console.log #i
f2: -> console.log 'hello'
class Child extends Test
run: ->
Test.f1()
hello = new Child()
hello.run()
Notice, the i variable is static, so it doesn't make sense to set it in the constructor. Also, the f1 method is now static as well.
(I'm not an expert with CoffeeScript, so I'm not sure what the :: syntax is needed for.)
The constructor is being run when you create a new instance of Child. The problem is the way that you're invoking f1.
You don't want to say Test::f1(). You can just say #f1(), since Child is a subclass of Test. These are different in a very important way: Test::f1() does not set this, so when that function requests this.i, it finds only undefined, because this is set to Window (or something ridiculous like that in the browser, not sure if you're running this in Node). Saying #f1() is the same as saying Test::f1.call(this). This is one of the nice things that CoffeeScript's class system lets you do.
Finally, a pedantic note: there are no static variables in the code you've written. i, as you've written it, is an instance variable. Static variables look like this:
class Test
#staticVar = 1234
Or like this:
class Test
# ...
Test.staticVar = 1234
Instance variables look like this:
class Test
fn: ->
#instanceVar = 1234
Or like this:
test = new Test()
test.instanceVar = 1234
Or even like this (for the default value of an instance variable shared among all instances):
Test::instanceVar = 1234
In a similar vein:
When I call hello.run(), it calls Test.f1(), but the result is undefined. It's not setting the static variable #i before it's running Test.f1().
You're never calling Test.f1(); you're calling Test::f1(), which is very different. In the code you've written, there is no Test.f1, only Test.prototype.f1.
Hi I'm new to Js and Coffeescript, here's a situation I feel difficult to refer the property of parent object which is App in the following example
App =
init: ->
this.foo = 'bar'
this.bindEvent()
bindEvent: ->
$('#test').click(this.show)
show: ->
alert this.foo
App.init()
I think the fat arrow may do the trick but once I've changed to show: =>, this in the context of show method refers to the window object, instead of App object that I want to
. Anybody can tell me how to do it right?
http://jsfiddle.net/kZpHX/
When you define your show function, # (AKA this) actually is window so
show: => console.log(#)
will bind show to window. The problem is that you're simply defining an object so there isn't anything to bind to: you aren't defining a class so this is window. You could refer to App explicitly like this:
App =
#...
show: -> alert(App.foo)
Demo: http://jsfiddle.net/ambiguous/3sRVh/
The this.foo in init will do the right thing because saying App.init() sets up the expected this.
You could also hook up the desired this manually:
bindEvent: ->
$('#test').click => #show()
# or
bindEvent: ->
_this = # # JavaScript style
$('#test').click -> _this.show()
Demos: http://jsfiddle.net/ambiguous/byL45/, http://jsfiddle.net/ambiguous/MT8fG/
Or you could create a class for your App instead:
class App
constructor: ->
#foo = 'bar'
#bindEvent()
bindEvent: ->
$('#test').click(#show)
show: =>
console.log(#foo)
new App
That way your show: => will behave the way you expect it to.
Demo: http://jsfiddle.net/ambiguous/byatH/
I come from a C#/Java background which use a class based OO system and I don't get the JavaScript/CoffeeScript prototype OO system yet. I've written a CoffeeScript class below which allows me to display names for contacts according to a system-side preference. I can only get the class to work by making the joinNonEmpty(stringList, joinText) method belong to the prototype and calling it the way I would call a static method in Java/C# land.
Is there a way I can make this method call using this.joinNonEmpty(...)?
Can you shed some light on why I can reference the firstLastRender, lastFirstRender and firstOrNickThenLast methods in the constructor with this. but it doesn't work from those methods when calling the joinNonEmpty helper?
Does this have something to do with how I'm locating the appropriate method via the preference map?
prefs = displayNameFormat: "FirstOrNickThenLast"
class DisplayNameRenderer
constructor: ->
#prefToRenderMap =
FirstLast: this.firstLastRender
LastFirst: this.lastFirstRender
FirstOrNickThenLast: this.firstOrNickThenLast
# Why does this method have to be static (a class method)?
#joinNonEmpty: (stringList, joinText) ->
nonEmptyStrings = []
for s in stringList
nonEmptyStrings.push(s) if s isnt null and s isnt ""
nonEmptyStrings.join(joinText)
firstLastRender: (contact) ->
# TypeError: Object expected.
joinNonEmpty([contact.firstName, contact.lastName], ' ')
lastFirstRender: (contact) ->
# TypeError: Object doesn't support this method or property
this.joinNonEmpty([contact.lastName, contact.firstName], ', ')
firstOrNickThenLast: (contact) ->
# Works correctly.
DisplayNameRenderer.joinNonEmpty([(if contact.nickname isnt null and contact.nickname isnt "" then contact.nickname else contact.firstName), contact.lastName], ' ')
render: (contact) ->
#prefToRenderMap[prefs.displayNameFormat](contact)
contact = firstName: "Jonathan", nickname: "Jonny", lastName: "Appleseed"
dnr = new DisplayNameRenderer()
# => "Jonny Appleseed"
console.log dnr.render(contact)
Thanks for taking the time to answer.
this (AKA #) is determined when the function is called (with exceptions as below). So when you do this:
#prefToRenderMap =
FirstLast: this.firstLastRender
LastFirst: this.lastFirstRender
FirstOrNickThenLast: this.firstOrNickThenLast
You're storing unbound references to the three functions in the #prefToRenderMap instance variable and #prefToRenderMap is itself an object. Then you try to call the methods in your DisplayNameRenderer instance like this:
#prefToRenderMap[prefs.displayNameFormat](contact)
and everything falls apart because the methods are called in the wrong context and # isn't what they're expecting it to be. If prefs is 'FirstOrNickThenLast' then you're effectively doing this:
#prefToRenderMap.FirstOrNickThenLast(contact)
and # (AKA this) will be #prefToRenderMap inside the firstOrNickThenLast method. But, of course, #prefToRenderMap doesn't have any of the methods that you're trying to call so you get various errors.
One solution is to use the fat arrow (=>) to define the methods:
The fat arrow => can be used to both define a function, and to bind it to the current value of this, right on the spot.
So you could have things like this:
joinNonEmpty: (stringList, joinText) ->
#...
firstLastRender: (contact) =>
#joinNonEmpty([contact.firstName, contact.lastName], ' ')
and everything will work out. Here's a stripped down demo that will also show you your this problem:
http://jsfiddle.net/ambiguous/RAPJw/1/
You could also avoid this problem by referring to the methods by their names. Given a method name in a string, m = 'some_method', you can call that method like this o[m]() in both JavaScript and CoffeeScript and the result will be the same as if you said o.some_method(). A better structure would look more like this:
class DisplayNameRenderer
constructor: ->
#prefToRenderMap =
FirstOrNickThenLast: 'firstOrNickThenLast'
joinNonEmpty: (stringList, joinText) ->
#...
firstOrNickThenLast: (contact) ->
#joinNonEmpty([(if contact.nickname isnt null and contact.nickname isnt "" then contact.nickname else contact.firstName), contact.lastName], ' ')
render: (contact) ->
#[#prefToRenderMap['FirstOrNickThenLast']](contact)
Note the change to the structure of #prefToRenderMap and how it is used in render. And a demo of this approach: http://jsfiddle.net/ambiguous/DFYwu/
As an aside, instead of saying ClassName.class_method() inside an instance method, you can use the constructor property instead: #constructor.class_method(). Also, you usually say #method() or #property rather than this.method() and this.property in CoffeeScript.