More Memoization

C#, Programming by thegoldenmule

I had to cache the results a couple methods recently, and only after I had done it a few times, I realized I should just write a memoization extension for System.Func.

public static Func<T, TResult> Memoize<T, TResult>(this Func<T, TResult> func)
{
	Dictionary<T, TResult> dict = new Dictionary<T, TResult>();
 
	return input =>
		{
			if (!dict.ContainsKey(input))
			{
				dict[input] = func(input);
			}
 
			return dict[input];
		};
}

With this handy extension, I'm free to have fun with memoizing arbitrary Funcs.

Func<int, int> fib = n =>
	{
		int a = 0;
		int b = 1;
 
		for (int i = 0; i < n; i++)
		{
			int temp = a;
			a = b;
			b = temp + b;
		}
		return a;
	};
 
Func<int, int> memoizedFib = fib.Memoize();

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