counter.md

Counter

In this tutorial, we'll write a program that counts how many times it ran. We'll use a Chest<int> to store the counter.

First, create a new project. In the pubspec.yaml file, add chest as a dependency:

dependencies:
  chest: any

Add the following global variable:

final counter = Chest('counter', ifNew: () => 0);

Because the ifNew function returns an int, Dart will automatically infer that counter is a Chest<int>.

To actually be able to put an int into a chest and get it out again, we'll need to register a taper for the int type. Chest already comes with a handful of builtin tapers, so you can add the following at the beginning of your main method:

tape.register({
  ...tapers.forDartCore, // contains a taper for int
});

To use the chest, we'll need to open it. So, let's do that next:

await counter.open();

You'll need to make the main function async to be able to use await:

void main() async {
  ...
}

Now that the chest is opened, we can access its value:

print('This program ran ${counter.value} times.');

If you want to handle singular and plural correctly, you can instead use this snippet:

final count = counter.value;
print('This program ran $count ${count == 1 ? 'time' : 'times'}.');

Once we printed the counter, it's time to increase it:

counter.value++;

Finally, close the chest so that the chest file gets closed and the program can stop:

await counter.close();

And that's it!

If you run the program multiple times, you'll see that its output is different each time:

This program ran 0 times.
This program ran 1 time.
This program ran 2 times.
This program ran 3 times.
...

You can find the complete source code at TODO.