不支持的格式字符警告

Question

以下代码按预期工作：

class Item(object):
    def __init__(self, unq_id, name, price, qty, measure):
        self.unq_id = unq_id
        self.product_name = name
        self.price = price
        self.qty = qty
        self.measure = measure


class Cart(object):
    def __init__(self):
        self.content = dict()

    def __format__(self, format_type):
        if format_type == 'short':
            return ', '.join(item.product_name for item in self.content.values())

        elif format_type == 'long':
            return '\n'.join(f'\t\t{item.qty:2} {item.measure:7} {item.product_name:12} @ '
                             f'${item.price:1.2f} ... ${item.qty * item.price:1.2f}'
                             for item in self.content.values())

    def add(self, item):
        if item.unq_id not in self.content:
            self.content.update({item.unq_id: item})
            return
        for k, v in self.content.get(item.unq_id).items():
            if k == 'unq_id':
                continue
            elif k == 'qty':
                total_qty = v.qty + item.qty
                if total_qty:
                    v.qty = total_qty
                    continue
                self.remove_item(k)
            else:
                v[k] = item[k]

    def get_total(self):
        return sum([v.price * v.qty for _, v in self.content.items()])

    def get_num_items(self):
        return sum([v.qty for _, v in self.content.items()])

    def remove_item(self, key):
        self.content.pop(key)


if __name__ == '__main__':
    item1 = Item(1, "Cucumbers", 1., 1, 'kg')
    item2 = Item(2, "Tissues", 2., 2, 'dozen')
    item3 = Item(3, "Tomatoes", 3., 5, 'pound')
    item4 = Item(4, "Toothpaste", 1., 5, 'box')
    cart = Cart()
    cart.add(item1)
    cart.add(item2)
    cart.add(item3)
    cart.add(item4)
    print("Your cart contains: {0:short}".format(cart))
    # cart.remove_item(1)
    print()
    print("Your cart contains: \n {0:long}".format(cart))
    print()
    print("The total number of items in your cart is: ", cart.get_num_items())
    print()
    print("The total cost of the items in your cart is: ", cart.get_total())
    print()
    cart.remove_item(3)
    print("Your cart contains: {0:short}".format(cart))
    print()
    print("Your cart contains: \n {0:long}".format(cart))
    print()
    print("The total number of items in your cart is: ", cart.get_num_items())
    print()
    print("The total cost of the items in your cart is: ", cart.get_total())

我的问题是 PyCharm 就这段代码向我哭诉：

    print("Your cart contains: \n {0:long}".format(cart))

PyCharm 说我正在使用 "unsupported format character '|' " <-- 看起来像 PyCharm 内的竖线。由于一切正常，我不确定 PyCharm 在抱怨什么。我想知道 PyCharm 反对什么。

以上代码的输出：

Your cart contains: Cucumbers, Tissues, Tomatoes, Toothpaste

Your cart contains: 
         1 kg      Cucumbers    @ .00 ... .00
         2 dozen   Tissues      @ .00 ... .00
         5 pound   Tomatoes     @ .00 ... .00
         5 box     Toothpaste   @ .00 ... .00

The total number of items in your cart is:  13

The total cost of the items in your cart is:  25.0

Your cart contains: Cucumbers, Tissues, Toothpaste

Your cart contains: 
         1 kg      Cucumbers    @ .00 ... .00
         2 dozen   Tissues      @ .00 ... .00
         5 box     Toothpaste   @ .00 ... .00

The total number of items in your cart is:  8

The total cost of the items in your cart is:  10.0

Process finished with exit code 0

Answer 1

竖线是小写字母 L，它在格式字符串 long 的开头找到。它在抱怨，因为 PyCharm 只识别特定的字符子集（即 https://docs.python.org/2/library/string.html#format-specification-mini-language），因为它不知道搜索 __format__ 的运算符重载。不幸的是，我最好的建议是为 PyCharm 添加一个 noinspection 子句：

# noinspection PyStringFormat
print("Your cart contains: \n {0:long}".format(cart))

不支持的格式字符警告

Unsupported format character warning

string-formatting

python-3.6