Usage of "with" function

Question

is there somebody who can explain me what "with" function is used for?

Signature

public inline fun <T, R> with(receiver: T, f: T.() -> R): R = receiver.f()

Doc

Calls the specified function f with the given receiver as its receiver and returns its result.

And I found its using on this project Antonio Leiva. It was using for moving view :

fun View.animateTranslationY(translationY: Int, interpolator: Interpolator) {
    with(ObjectAnimator.ofFloat(this, "translationY", translationY.toFloat())) {
        setDuration(context.resources.getInteger(R.integer.config_mediumAnimTime).toLong())
        setInterpolator(interpolator)
        start()
    }
}

I was thinking that I know the meaning to I transfer it to

fun View.animateTranslationX(translationX: Int, interpolator: Interpolator) {
    with(ObjectAnimator()) {
        ofFloat(this, "translationX", translationX.toFloat())
        setDuration(context.resources.getInteger(R.integer.config_mediumAnimTime).toLong())
        setInterpolator(interpolator)
        start()
    }
}

but it doesn't compile ... But I think that ObjectAnimaton is receiver and it get everything what I will call in {} bracket. Can anybody explain the real meaning and provide a basic example - at least more basic than this? :D

Answer 1

The idea is the same as with keyword in Pascal.
Anyway, here are three samples with identical semantic:

with(x) {
   bar()
   foo()
}

with(x) {
   this.bar()
   this.foo()
}

x.bar()
x.foo()