Added "when", which will only execute when initial condition is met

[JiriTrecak]

I propose we add one more function - when. This serves exactly the same purpose, but "then" is only executed when initial condition is met. This is extremely useful in a lot of cases, as it changes often used syntax

if (true) {
    label.then {
        ...
    }
}

to

label.when(true) {
    ...
}

The only problem is that it does not fit with name of your repository :D but I think it is okay :)

[devxoul]

@JiriTrecak, cool. How can we use it in real-world?

[JiriTrecak]

I mean, there is ton of stuff, but if you want one concrete example:

profilePicture.when(Model.currentUser.isLoggedIn) {
    $0.image = UIImage("avatar")
}

[devxoul]

I'm not sure. Why not use:

if Model.currentUser.isLoggedIn {
    profilePicture.image = UIImage("avatar")
}

I think it's more clear.

[JiriTrecak]

You are definitely right, but your example uses only one assign, which makes even .then {} useless

profilePicture.when(Model.currentUser.isLoggedIn) {
    $0.image = UIImage("avatar")
    $0.backgroundColor = .clearColor
    $0.layer.cornerRadius = 2.0
}

This is definitely consistent with your idea of the usage, and I am sure others can come with very clever uses of this (personally, I use .then in cells extensively - and this is where I'd like to have option like this).

[devxoul]

Of course then() can be used with existing objects (e.g. profilePicture as you mentioned), but then() was originally designed to provide a simple way to initialize properties.

Imagine that we have an UILabel as a property. We can define this label, an also able to create an instance of it. However, we have to initialize label's properties in another location: init().

class MyClass {
    let label = UILabel() // define and create an instance at here, but...

    init() {
        // initialize properties at here (why?)
        self.label.textColor = .blackColor()
        self.label.text = "Hi"
    }
}

then() solves it by using closures.

class MyClass {
    // define and create an instance, then initialize properties
    let label = UILabel().then {
        $0.textColor = .blackColor()
        $0.text = "Hi"
    }
}

This is why I asked you for a real-world example. I think when() is out of then()'s philosophy and can be replaced with if statement.