Python 它将构建字典缓存，直到try语句工作，一旦try语句工作，它将返回结果并完成…print语句如何工作？如果FibonacciStorage.\u fib（1号）正在被立即调用？或者是否存在延迟（在执行递归之前是否等待函数结束）？抱歉，这是我感到困惑的地方.

---

它将构建字典缓存，直到try语句工作，一旦try语句工作，它将返回结果并完成…print语句如何工作？如果FibonacciStorage.\u fib（1号）正在被立即调用？或者是否存在延迟（在执行递归之前是否等待函数结束）？抱歉，这是我感到困惑的地方..只要值不在缓存中，就会在添加后立即调用print语句。我认为你应该跟踪程序的执行情况，以便更好地理解它，使用调试器。好的。以前从未这样做过，但我会查找跟踪。谢谢奥斯卡。

# Fibonacci recursive with result storage

class FibonacciStorage:
    _storage = { 0:1, 1:1 }
    @staticmethod
    def _fib(number):
        try: # is this already calculated
            return FibonacciStorage._storage[number]   #searches dict, and if value exists then return it
        except KeyError:
            result = FibonacciStorage._fib(number-1) + FibonacciStorage._fib(number-2)  #this is the actual Fibonacci Formula
            FibonacciStorage._storage[number] = result  #adds result to dictionary
            #print FibonacciStorage._storage #this shows the storage list growing with each iteration.
            return result
    @staticmethod
    def fib(number):  #first function, it has two asserts to basically make sure number is whole/positive and if its okay passes it to _fib(where the real work is done)
        # only do the assert statements once
        assert(isinstance(number,int)),"Needs a whole number" 
        assert(number>0),"Needs a positive whole number"
        return FibonacciStorage._fib(number)

# use a more readable name
getFib = FibonacciStorage.fib

print getFib(50)

result = FibonacciStorage._fib(number-1) + FibonacciStorage._fib(number-2)
//                   here ^                        and here ^

                                 fib(4)
                               /        \
                          fib(3)   +     fib(2)
                         /    \          /     \
                    fib(2) + fib(1)   fib(1) + fib(0)
                    /    \
               fib(1) + fib(0)

class FibonacciStorage(dict):
    def __missing__(self, n):
        self[n] = self[n - 1] + self[n - 2]
        return self[n]

fib = FibonacciStorage({0: 1, 1: 1})
print(fib[50]) #20365011074