Python优化：如何避免for循环与range的结合使用？

我编写了一个输入函数，用于从指定数量的产品中选择产品并进行错误处理。目前我使用了for i in range(no_of_products_sel)的写法，这种方式不够Pythonic，应该可以不借助range实现迭代，但我未能成功。以下是我的部分代码：

valid_expression = False # for next while loop
while valid_expression is False:
    products = []

    for i in range(no_of_products_sel):
        products_confirmed = False # for next while loop
        while products_confirmed is False:
            product = input(f"Please enter product name {i+1}:")
            if product.lower().strip() == "exit":
                print("See you soon!")
                return None
            product_clean = product.lower().title().strip()
            if product_clean in products:
                print(f"Already chosen! Choose another product!")

            elif product_clean in list_of_products:
                products.append(product_clean)
                products_codes[product_clean]=product_codes(product)  # get product codes, save them in dict
                product_confirmed = True  # 注意：原代码此处变量名拼写错误，应为products_confirmed

            elif product_clean not in list_of_products:
                print(f"\n---\nYou have entered '{product}', which is not in the stock. Enter another product!\n---\n")

        valid_expression = True

解决方案：用while循环基于列表长度判断，替代range循环 #

核心思路是：我们的目标是收集指定数量的有效产品，而非单纯执行N次循环。直接通过判断products列表的长度来控制迭代，既贴合业务逻辑，又避免了冗余的索引变量，更符合Pythonic风格。

修改后的代码示例：

valid_expression = False
while not valid_expression:
    products = []
    # 只要收集的产品数量未达要求，就继续循环
    while len(products) < no_of_products_sel:
        products_confirmed = False
        # 用已选产品数量+1来提示用户当前是第几个输入项
        product_num = len(products) + 1
        while not products_confirmed:
            product = input(f"Please enter product name {product_num}:")
            if product.lower().strip() == "exit":
                print("See you soon!")
                return None
            product_clean = product.lower().title().strip()
            
            if product_clean in products:
                print(f"Already chosen! Choose another product!")
            elif product_clean in list_of_products:
                products.append(product_clean)
                products_codes[product_clean] = product_codes(product)
                products_confirmed = True  # 修正原代码的变量名拼写错误
            else:
                print(f"\n---\nYou have entered '{product}', which is not in the stock. Enter another product!\n---\n")
    valid_expression = True

为什么这样更Pythonic？ #

• 关注点从“循环次数”转移到“业务目标（收集足够产品）”，代码可读性更强
• 无需维护额外的索引变量i，减少冗余代码
• 逻辑更直观：只要没收集够指定数量，就继续请求输入

内容的提问来源于stack exchange，提问作者Martha's Vineyard