Beginner Python: AttributeError: list object has no attribute

Beginner Python: AttributeError: list object has no attribute

Consider:

class Bike(object):
    def __init__(self, name, weight, cost):
        self.name = name
        self.weight = weight
        self.cost = cost

bikes = {
    # Bike designed for children
    Trike: Bike(Trike, 20, 100),      # <--
    # Bike designed for everyone
    Kruzer: Bike(Kruzer, 50, 165),    # <--
    }

# Markup of 20% on all sales
margin = .2
# Revenue minus cost after sale
for bike in bikes.values():
    profit = bike.cost * margin
    print(profit)

Output:

33.0
20.0

The difference is that in your bikes dictionary, youre initializing the values as lists [...]. Instead, it looks like the rest of your code wants Bike instances. So create Bike instances: Bike(...).

As for your error

AttributeError: list object has no attribute cost

this will occur when you try to call .cost on a list object. Pretty straightforward, but we can figure out what happened by looking at where you call .cost — in this line:

profit = bike.cost * margin

This indicates that at least one bike (that is, a member of bikes.values() is a list). If you look at where you defined bikes you can see that the values were, in fact, lists. So this error makes sense.

But since your class has a cost attribute, it looked like you were trying to use Bike instances as values, so I made that little change:

[...] -> Bike(...)

and youre all set.

They are lists because you type them as lists in the dictionary:

bikes = {
    # Bike designed for children
    Trike: [Trike, 20, 100],
    # Bike designed for everyone
    Kruzer: [Kruzer, 50, 165]
    }

You should use the bike-class instead:

bikes = {
    # Bike designed for children
    Trike: Bike(Trike, 20, 100),
    # Bike designed for everyone
    Kruzer: Bike(Kruzer, 50, 165)
    }

This will allow you to get the cost of the bikes with bike.cost as you were trying to.

for bike in bikes.values():
    profit = bike.cost * margin
    print(bike.name +  :  + str(profit))

This will now print:

Kruzer : 33.0
Trike : 20.0

Beginner Python: AttributeError: list object has no attribute

You need to pass the values of the dict into the Bike constructor before using like that. Or, see the namedtuple — seems more in line with what youre trying to do.