memoized 2.2.1

Decorators to cache returned values, it helps in reducing the execution time of the function by using LRU Caching.

Overview

The memoized package is designed to store the previously computed value of a function so that if the function is called again with the same parameters, the stored value is returned immediately instead of recalculating it.

Features

Memoization: Wraps a function and caches its result.

import 'package:memoized/memoized.dart'; 

final sum = (() => 1.to(999999999).sum()).memo;
print(sum());  // Computes the sum
print(sum());  // Returns the cached sum

LRU Cache: For functions that accept parameters, an LRU (Least Recently Used) cache is maintained. It caches the results of the most recent function calls based on their parameters.

import 'package:memoized/memoized.dart';

// Memoized1<ReturnType, ArgumentType>
late final Memoized1<int, int> fib;
fib = Memoized1((int n) {
  if (n <= 1) return n;
  return fib(n-1) + fib(n-2);
});
print(fib(80));

Expiry: Allows you to manually expire the cached value.

Iterable<int> numbers = 1.to(30000000);
final calculateSum = (() => numbers.sum()).memo;

numbers = 1.to(9043483);
calculateSum.expire();     // Cache is cleared but not computed

final value = calculateSum();  // Recomputed here

Within a Class: You can use memoized functions within classes too.

class IntervalTimer {
  final List<Duration> timers = [];
  late final totalDuration = _totalDurationImpl.memo;

  Duration _totalDurationImpl() => timers.fold<Duration>(
    Duration.zero,
    (p, v) => p + v
  );
}