CODEWITHSUNDEEP
pythonpython-3.x
AlexW
AlexW

Reputation: 2589

Set name of object in class

I want to set the name of a class to one of the variables within the class so that when I print classes I get their names, I've tried setting __name__ but it did not work.

this is my class

class SNMPData(object):
    def __init__(self, device='', speed_down=0, speed_up=0, bgp_peer_state='', bgp_summary='', error=''):
        self.device = device
        self.speed_down = speed_down
        self.speed_up = speed_up
        self.bgp_peer_state = bgp_peer_state
        self.bgp_summary = bgp_summary
        self.error = error
        self.__name__ = device

I create a list of objects then try print them

>>> list = [SNMPData(device='dev_1',speed_down=1),SNMPData(device='dev_2',speed_down=2)]
>>> print(list)
[<SNMPData object at 0x7ff052a42ef0>, <SNMPData object at 0x7ff052a42b38>]
>>>

instead of SNMPData object at 0x.... is it possible to print 

['SNMPData dev_1','SNMPData dev_2']

instead?

Upvotes: 3

Views: 8480

Answers (5)

Arda Arslan
Arda Arslan

Reputation: 1361

Generalizing some of the other answers, you could do:

def __str__(self):
    return '{self.__class__.__name__} {self.device}'.format(self=self)

Upvotes: 1

OLIVER.KOO
OLIVER.KOO

Reputation: 5993

You are looking to define __repr__ which should return a printable representation of the object. The official definition of __repr__

repr(object):

Return a string containing a printable representation of an object. For many types, this function makes an attempt to return a string that would yield an object with the same value when passed to eval(), otherwise the representation is a string enclosed in angle brackets that contains the name of the type of the object together with additional information often including the name and address of the object. A class can control what this function returns for its instances by defining a repr() method.

bottom line is that the output from __str__ is meant to be readable by human ** whereas the output from **__repr__ is meant to be read by the Python interpreter. so when you give the string to the interpreter, it should recreate the object. Also If an object doesn't have a __str__ method then __repr__ is used instead.

Upvotes: 5

hyperneutrino
hyperneutrino

Reputation: 5425

Each class has a __repr__ and __str__ function which takes a single argument, self, representing the object itself. The __repr__ function returns the true string representation of the object and the __str__ function is used for str(obj) which is used for printing.

class SNMPData(object):
    def __init__(self, device='', speed_down=0, speed_up=0, bgp_peer_state='', bgp_summary='', error=''):
        ...
    def __repr__(self):
        return '{} {}'.format(self.__class__.__name__, self.device)

You can do the same for __str__(self) if you want to observe this behaviour for printing.

Upvotes: 3

RomanPerekhrest
RomanPerekhrest

Reputation: 92854

You are able to change a text representation of your custom object by overriding __repr__ and __str__ methods:

...
def __repr__(self):
    return self.__class__.__name__ + ' ' + self.device

Upvotes: 2

erip
erip

Reputation: 16935

Define __repr__(self) and __str__(self).

The former is the "official" string representation. The latter is what is returned when you cast the object to a str.

Upvotes: 1

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