[dart-misc] What is equialent with this in Dart ?

[Kovács Attila]

Hi

I have a short sample code in Go :

package main

import (
"fmt"
"time"
)

func numbers() {
for i := 1; i <= 5; i++ {
time.Sleep(250 * time.Millisecond)
fmt.Printf("%d ", i)
}
}
func alphabets() {
for i := 'a'; i <= 'e'; i++ {
time.Sleep(400 * time.Millisecond)
fmt.Printf("%c ", i)
}
}
func main() {
go numbers()
go alphabets()
time.Sleep(3000 * time.Millisecond)
fmt.Println("main terminated")
}

You can try it in go playground.

I need the equialent code in Dart. (I'm learning async and await, but i
don't understand it yet.)
Could anybody help me a little bit.

Thank you Attila

['Lasse R.H. Nielsen' via Dart Misc]

A somewhat equivalent program in Dart would be:

const ms = Duration(milliseconds: 1);
void numbers() async {
for (var i = 1; i <= 5; i++) {
await Future.delayed(ms * 250);
print(i);
}
}
void alphabets() async {
var a = "a".codeUnitAt(0);
var e = "e".codeUnitAt(0);
for (var i = a; i <= e; i++) {
await Future.delayed(ms * 400);
print(String.fromCharCode(i));
}
}
void main() async {
numbers();
alphabets();
await Future.delayed(ms * 3000);
print("main terminated");
}


That is not necessarily how I would write that program in Dart. You would
usually not make fire-and-forget functions and then wait for an equivalent
duration.
Instead I'd more likely write it as:

const ms = Duration(milliseconds: 1);
Future<void> numbers() async {
for (var i = 1; i <= 5; i++) {
await Future.delayed(ms * 250);
print(i);
}
}
Future<void> alphabets() async {
var a = "a".codeUnitAt(0);
var e = "e".codeUnitAt(0);
for (var i = a; i <= e; i++) {
await Future.delayed(ms * 400);
print(String.fromCharCode(i));
}
}
void main() async {
await Future.wait([numbers(), alphabets()]);
print("main terminated");
}


Alternatively, if you are not going to await the async functions anyway,
you can use timers instead:

import "dart:async";const ms = Duration(milliseconds: 1);
void numbers() {
int i = 1;
Timer.periodic(ms * 250, (t) {
print(i);
i++;
if (i > 5) t.cancel();
});
}
Future<void> alphabets() async {
var string = "abcde";
var i = 0;
Timer.periodic(ms * 400, (t) {
print(string[i]);
i++;
if (i >= string.length) t.cancel();
});
}
void main() {
numbers();
alphabets();
Timer(ms * 3000, () {
print("main terminated");
});
}


Hope this helps.
/L

Post by Kovács Attila
Hi
package main
import (
"fmt"
"time"
)
func numbers() {
for i := 1; i <= 5; i++ {
time.Sleep(250 * time.Millisecond)
fmt.Printf("%d ", i)
}
}
func alphabets() {
for i := 'a'; i <= 'e'; i++ {
time.Sleep(400 * time.Millisecond)
fmt.Printf("%c ", i)
}
}
func main() {
go numbers()
go alphabets()
time.Sleep(3000 * time.Millisecond)
fmt.Println("main terminated")
}
You can try it in go playground.
I need the equialent code in Dart. (I'm learning async and await, but i
don't understand it yet.)
Could anybody help me a little bit.
Thank you Attila
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Lasse R.H. Nielsen - ***@google.com
'Faith without judgement merely degrades the spirit divine'
Google Denmark ApS - Frederiksborggade 20B, 1 sal - 1360 KÞbenhavn K
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[Kovács Attila]

Thank you Sir for your abundant explanation
It help me a lot.
Attila

Post by Kovács Attila
Hi
package main
import (
"fmt"
"time"
)
func numbers() {
for i := 1; i <= 5; i++ {
time.Sleep(250 * time.Millisecond)
fmt.Printf("%d ", i)
}
}
func alphabets() {
for i := 'a'; i <= 'e'; i++ {
time.Sleep(400 * time.Millisecond)
fmt.Printf("%c ", i)
}
}
func main() {
go numbers()
go alphabets()
time.Sleep(3000 * time.Millisecond)
fmt.Println("main terminated")
}
You can try it in go playground.
I need the equialent code in Dart. (I'm learning async and await, but i
don't understand it yet.)
Could anybody help me a little bit.
Thank you Attila