---
title: Computed API docs
description: All the API docs of Computed
---

# Computed API docs

A special Signal that notifies only whenever the selected values change.

A __Computed__ extends a [ReadSignal](/api-docs/read-signal), so all the API of __ReadSignal__ are available.

## Constructor

```dart
Computed(
  T Function() selector, {
  SignalOptions<T>? options,
});
```

`selector` is the function used to compute the value of the signal.

`options` are the [options](/api-docs/signal-options) of the signal.

```dart
final count = Signal(1);
final doubleCount = Computed(() => count() * 2);
print(doubleCount()); // prints 2
count.set(2);
print(doubleCount()); // prints 4
```