memoized 1.3.0

Decorators to simply cache function return values.

Installing

dependencies:
  memoized:

import 'package:memoized/memoized.dart';

Memoized

Wrap a function to store the previously computed value and return this value on the next call.

• Basic

  Iterable<int> numbers = 1.to(30000000);
  final calculateSum = (() => numbers.sum()).memo;
    
  print(time(calculateSum));
  print(time(calculateSum));  // It returns the memoized value.
  

• expire

  Iterable<int> numbers = 1.to(30000000);
  final calculateSum = (() => numbers.sum()).memo;
  print(calculateSum());
    
  numbers = 1.to(9043483);
  calculateSum.expire()  // not computed
    
  numbers = 1.to(45000000);
  calculateSum.expire()  // not computed
    
  final value = calculateSum()   // recomputed at this point.
  

• in Class

  class IntervalTimer {
    final List<Duration> timers = [/* durations */];
        
    late final totalDuration = _totalDurationImpl.memo;
    Duration _totalDurationImpl() => timers.fold<Duration>(
      Duration.zero,
    	(p, v) => p + v
    );
  }
  

Memoized1

Decorator to wrap a function with a memoizing callable that saves up to the capacity most recent calls.

• fibonacci

  // 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(90));
    
  

• async

  late final Memoized1Async<String, String> fetchDocument;
  fetchDocument = Memoized1Async((url) async {
    await Future.delayed(const Duration(seconds: 2));
    if (url == 'hello') return 'hello, memoized';
    return 'welcome';
  });
    
  print(await fetchDocument('hello'));
  print(await fetchDocument('hello')); // returned immediately
  print(await fetchDocument('test'));
  print(await fetchDocument('test')); // returned immediately
  

• expire

  print(await fetchDoument('hello')); // returned after 2 seconds.
  fetchDocument.expire('hello');
  print(await fetchDoument('hello')); // also returned after 2 seconds.
  

• in Class

  class Test {
    late final Memoized1<int, int> fib = Memoized1(
      (n) => n <= 1 ? n : fib(n - 1) + fib(n - 2),
    );
  }
  

• capacity

  late final Memoized1Async<String, String> fetchDocument;
  fetchDocument = Memoized1Async(
    (url) async {
      await Future.delayed(const Duration(seconds: 2));
      if (url == 'hello') return 'hello, memoized';
      return 'welcome';
    },
    capacity: 10,  // modified, default == 128
  );