CODEWITHSUNDEEP
pythonpython-3.xclass
Federico Di Lembo
Federico Di Lembo

Reputation: 61

Is there a way to print all the parameters of the objects created in the __init__ method?

This is the code I'm working on. I created some users, giving them a name, surname and a value.

Is there a way to return and print all, for instance, name of every user I created?

class Bacheca:

    def __init__(self, name, surname, value):
        self.name = name
        self.surname = surname
        self.value = value

user1 = Bacheca("John", "Black", 1)
user2 = Bacheca("Mark", "Green", 2)
user3 = Bacheca("Phil", "White", 3)

What I would like it's to print, for example, all the name of each users:

John 
Mark
Phil

Is it possibile?

Thank you for your time.

Upvotes: 2

Views: 100

Answers (2)

Error - Syntactical Remorse
Error - Syntactical Remorse

Reputation: 7887

The other answer is creative solution that I may have a use for in the future but caution should be taken with it. As noted in the comments it will keep a reference to your class instances, thus the garbage collector won't delete them properly (i.e. none of the class instances will be deleted until the last instance is unused [even then it may act funky and not delete properly]). There are ways around this (such as weakref or using the __del__ magic method) but if you are more of a novice I would probably avoid it. If all you want is a list then make a list:

users = []
users.append(Bacheca("John", "Black", 1))
users.append(Bacheca("Mark", "Green", 2))
users.append(Bacheca("Phil", "White", 3))

for user in users:
    print(user.name)
# or
print([user.name for user in users])

Also if you aren't doing anything else with your class and you are just using it to group attributes together then you may want to use a namedtuple.

from collections import namedtuple
Bacheca = namedtuple('Bacheca', 'name surname value')

# it acts the same as your class
users = []
users.append(Bacheca("John", "Black", 1))
users.append(Bacheca("Mark", "Green", 2))
users.append(Bacheca("Phil", "White", 3))

for user in users:
    print(user.name)

Upvotes: 1

gmds
gmds

Reputation: 19885

If you want to do it in the object itself, use a class variable in conjunction with a static method:

class Bacheca:

    created_users = []

    def __init__(self, name, surname, value):
        self.name = name
        self.surname = surname
        self.value = value
        Bacheca.created_users.append(self)

    @staticmethod
    def created():
        return Bacheca.created_users

user1 = Bacheca("John", "Black", 1)
user2 = Bacheca("Mark", "Green", 2)
user3 = Bacheca("Phil", "White", 3)
print([user.name for user in Bacheca.created()])

Output:

['John', 'Mark', 'Phil']

Every time __init__ is called (for initialisation of a new instance), the created object will be appended to created_users, which is a variable of the class, as opposed to an instance. Therefore, it persistently holds a reference to every instance that has been created.

You could add more bells and whistles by, say, overriding __del__, but that is probably beyond the scope of this question.

Upvotes: 2

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