Question

我在这里是新手，而while循环中的else，if语句过多。我想将其重构为功能，但我不知道如何执行。

我的代码：

brand = input("Please select a brand...")
        if brand.lower() == "XX" or sex == "1":
            print("You selected a XX...")
            while True:
                product = input()
                if product.lower() == "apple" or product == "1":
                    print("You selected Apples!\n")
                    while True:
                        size_schema = input()
                        if size_schema.lower() == "in" or size_schema.lower() == "inch" or size_schema == "1":
                            while True:
                                apple_size = float(input())
                                if 8.5 <= apple_size <= 12.0:
                                    real_apple_size = round(apple_size, 2)
                                    print("Your apple size is {} inch!".format(real_apple_size))
                                    cursor = size_guide.find({})
                                    for document in cursor:
                                        a = document['Product']['Apple']['INCH']
                                        try:
                                            b = [float(x) for x in a if x != '']
                                            result = min(enumerate(b), key=lambda i: abs(i[1] -
                                                                                         float(real_apple_size)))
                                            c = str(result[1])
                                        except ValueError:
                                            pass
                                        real_apple_size = str(real_apple_size)
                                        if real_apple_size in document['Product']['Apple']['INCH']:
                                            index = document['Product']['Apple']['INCH'].index(real_apple_size)
                                            print("We have this apples from {} brand!"
                                                  .format(document['Brand']))
                                        elif c in document['Product']['Apple']['INCH']:
                                            last_list_value = next(s for s in reversed(a) if s)
                                            index = document['Product']['Apple']['INCH'].index(c)
                                            real_apple_size = float(real_apple_size)
                                            print("SORRY! We don't have exactly your size, "
                                                  "but we have similar size from {} brand!"
                                                      .format(document['Brand']))
                                        else:
                                            print("Sorry, We don't have apples for you from {} brand!"
                                                  "Check our other products!"
                                                  .format(document['Brand']))
                                else:
                                    print("Please select your apple size in range 8.5-12.0 inch!")
                                    continue
                                break

我想减少这段代码并将其插入函数中。

Answer 1

首先，将整个内容包装在一个函数中

def foo():
    brand = input("Please select a brand...")
    if brand.lower() == "XX" or sex == "1":
        # etc.

现在，请注意，您的第一个if语句包含了该函数的其余部分，并且没有else子句。也就是说，如果条件失败，您将陷入该函数的结尾并隐式返回。因此，如果条件不成立，则只需显式返回即可。这样一来，您就可以立即使用大量代码。

def foo():
    brand = input("Please select a brand...")
    if brand.lower() != "XX" and sex != "1":
        return

    print("You selected a XX...")
    # etc

为每个else少的if语句重复此过程，返回或退出封闭的无限循环。

Answer 2

更好的（虽然可能不是最好的）功能代码将是一组可重用的函数，并且每个函数都执行一个（或很少）一件事情。例如：

def get_product():
    brand=input("What brand?")
        #input validation logic
    product=input("What product?")
        #input validation for product given brand
    size=input("What size?")
        #input validation given brand and product
    color=input("What color? (enter 'none' for no color)")
        #That's right, more validation
    return brand, prod, size, color

def prod_lookup(brand, prod, size, color):
    cursor = size_guide.find({})
    for document in cursor:
        #lookup product with logic as in your post

if __name__ == "__main__":
    brand, prod, size, color = get_product()
    prod_lookup(brand, prod, size, color)

同样，这只是一种减少混乱的方式的示例。例如，如果您需要更新可用产品列表，则只需调整一个功能的一部分，而无需从一堆嵌套的条件和循环中进行选择。

我肯定有更好的方法，但是希望这可以使您知道从哪里开始思考。

通过产品查找添加一种可能的输入验证实现。这样，您的brand将始终是产品编号而不是字符串，这通常是一个更快的查找：

brand_dict={'xx':'1','yy':'2'}

while True:
    brand=input("Enter brand: ").lower()
    if brand in brand_dict.keys():
        brand=int(brand_dict[brand])
        break
    elif brand in brand_dict.values():
        brand=int(brand)
        break
    else:
        print("Brand not recognized. Try again!")

如果Elif语句起作用，如何重构while循环过多

2 个答案: