CODEWITHSUNDEEP
pythonfunctionclassattributes
omEchan
omEchan

Reputation: 95

Python move from attribute to his class

Suppose I have this code:

class abc():

    def __init__(self):
        self.a = 0


def somefunc(var):
    pass


if __name__ == "__main__":
    aaa = abc()
    somefunc(aaa.a)

Now my question, there is a way to get an instance of the class (aaa) by his attribute (a) that passed to "somefunc" if I have only the attribute? In other words, to move from attribute to his class.

I know that is not popular to do that but I have some situation that forces me to.

Thank you for help!!!!

Upvotes: 0

Views: 314

Answers (3)

robobrno
robobrno

Reputation: 61

You can use instance as a parameter.

class abc():

    def __init__(self, num):
        self.a = num

def somefunc(var):
    print(var.a)

if __name__ == "__main__":
    aaa = abc(2)
    somefunc(aaa)
    bbb = abc(4)
    somefunc(bbb)

Upvotes: 0

soyapencil
soyapencil

Reputation: 629

You can if you really want to, but I wouldn't advise it.

class abc():
    def __init__(self,a):
        self.a = a

def somefunc(value):
    vars_dict = globals()         # swap this for whatever dictionary of variables you wish to use 
    abcs = [vars_dict[i] for i in vars_dict if isinstance(vars_dict[i],abc)]
    return [instance for instance in abcs if instance.a == value]

if __name__ == "__main__":
    instance1 = abc(1)
    instance2 = abc(2)
    instance3 = abc(1)
    print('1s: {}'.format(str(somefunc(1))))
    print('2s: {}'.format(str(somefunc(2))))
    print('3s: {}'.format(str(somefunc(3))))

This grabs from vars_dict all instances with which instance.a == value. I've implemented the globals() dict here, but you can swap it out for another dictionary as is appropriate.

Enjoy!

Upvotes: 0

quamrana
quamrana

Reputation: 39404

The answer is no.

Suppose I have this code:

class abc():
    def __init__(self):
        self.a = []


def somefunc(var):
    pass


if __name__ == "__main__":
    aaa = abc()
    bbb = abc()
    bbb.a = aaa.a
    somefunc(aaa.a)

Now should somefunc determine that it should refer to aaa or bbb?

Upvotes: 2

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