lesson 3 update

This commit is contained in:
Alexander Nozik 2021-04-02 18:54:42 +03:00
parent 967c5b0155
commit 6631dba59b
6 changed files with 30 additions and 11 deletions

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@ -6,6 +6,8 @@ object AClass{
val c = "c" val c = "c"
} }
fun getAClass(): AClass? = null
/** /**
* [with]/[run]/[let] are used to create a scope with given argument or receiver * [with]/[run]/[let] are used to create a scope with given argument or receiver
*/ */
@ -14,20 +16,20 @@ fun main() {
println("a = ${AClass.a}, b= ${AClass.b}, c = ${AClass.c}") println("a = ${AClass.a}, b= ${AClass.b}, c = ${AClass.c}")
// Using `with` // Using `with`
with(AClass){ val res = with(AClass){
// AClass type is the receiver in this scope // AClass type is the receiver in this scope
println("a = $a, b = $b, c = $c") println("a = $a, b = $b, c = $c")
return@with "some value" return@with "some value"
} }
//using `run` //using `run`
AClass.run { getAClass()?.run {
// the same as above // the same as above
println("a = $a, b= $b, c = $c") println("a = $a, b= $b, c = $c")
} }
//Using `let` to compose result. Not recommended to use without a need //Using `let` to compose result. Not recommended to use without a need
val letResult = AClass.let { val letResult = getAClass()?.let { arg ->
it.c + it.a arg.c + arg.a
} }
} }

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@ -17,6 +17,8 @@ fun main() {
*/ */
fun getAndIncrement() = i.also { i += 1 } fun getAndIncrement() = i.also { i += 1 }
println(getAndIncrement())
/** /**
* Configure properties of an object (apply) * Configure properties of an object (apply)
* https://kotlinlang.org/docs/idioms.html#configure-properties-of-an-object-apply * https://kotlinlang.org/docs/idioms.html#configure-properties-of-an-object-apply

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@ -29,9 +29,12 @@ fun main() {
val newList = list + "f" + mutableList val newList = list + "f" + mutableList
println(newList)
//Bonus //Bonus
val lambdaList = List(3){it.toString()} val lambdaList = List(3){it.toString()}
println(lambdaList)
} }
/** /**

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@ -15,5 +15,11 @@ fun main() {
println("$k -> $v") println("$k -> $v")
} }
map.forEach { (k, v) -> println("$k -> $v")}
val (a, b) = Pair(1, 2) val (a, b) = Pair(1, 2)
val coord = doubleArrayOf(0.0, 1.0, 2.0)
val (x,y,z) = coord
} }

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@ -7,5 +7,5 @@ class AClassWithList{
fun main() { fun main() {
val obj = AClassWithList() val obj = AClassWithList()
obj.list
} }

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@ -1,13 +1,17 @@
@file:JvmName("Idiom26Kt")
package lesson3 package lesson3
import kotlin.math.PI import kotlin.math.PI
import kotlin.math.sin import kotlin.math.sin
fun main() { fun main() {
fun integrate(from: Double = 0.0, to: Double = 1.0, step: Double = 0.01, function: (Double) -> Double): Double { fun integrate(
from: Double = 0.0,
to: Double = 1.0,
step: Double = 0.01,
function: (Double) -> Double,
): Double {
require(to > from) require(to > from)
require(step > 0)
var sum = 0.0 var sum = 0.0
var pos = from var pos = from
while (pos < to) { while (pos < to) {
@ -17,7 +21,9 @@ fun main() {
return sum return sum
} }
integrate { x -> x * x + 2 * x + 1 } integrate { x ->
x * x + 2 * x + 1
}
integrate(0.0, PI) { sin(it) } integrate(0.0, PI) { sin(it) }
integrate(0.0, PI, step = 0.02) { sin(it) } integrate(0.0, PI, step = 0.02) { sin(it) }
} }