Unsupported format character warning - string-formatting

Question

The following code works as intended:
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())
My question is that PyCharm is crying at me regarding this piece of code:
print("Your cart contains: \n {0:long}".format(cart))
PyCharm says I am using an "unsupported format character '|' " <-- Looks like a vertical bar inside of PyCharm. Since everything is working I am not sure what PyCharm is complaining about. I would like to know what PyCharm is objecting to.
Output from above code:
Your cart contains: Cucumbers, Tissues, Tomatoes, Toothpaste
Your cart contains:
1 kg Cucumbers # $1.00 ... $1.00
2 dozen Tissues # $2.00 ... $4.00
5 pound Tomatoes # $3.00 ... $15.00
5 box Toothpaste # $1.00 ... $5.00
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 # $1.00 ... $1.00
2 dozen Tissues # $2.00 ... $4.00
5 box Toothpaste # $1.00 ... $5.00
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

That vertical bar is the lowercase letter L, which it found in the beginning of the format string long. It's complaining since PyCharm only recognises a certain subset of characters (namely https://docs.python.org/2/library/string.html#format-specification-mini-language), as it doesn't know to search for operator overloading of __format__.
Unfortunately, my best advice is to add a noinspection clause for PyCharm to pick up:
# noinspection PyStringFormat
print("Your cart contains: \n {0:long}".format(cart))