Introduction
In Python, every thing is an object – from integers and strings to courses and features. This will appear odd, particularly for primitive varieties like numbers, however even these have attributes, like actual and imag. Every object has its personal attributes, that are mainly juset properties or traits that assist outline the item.
On this Byte, we’ll discover other ways to get all attributes of an object in Python, and the way to show and manipulate them successfully.
Viewing Object Attributes
To start out with, let us take a look at how we are able to view the attributes of an object in Python. Python gives a built-in operate, dir(), which returns an inventory of all attributes and strategies of an object, which additionally contains these inherited from its class or dad or mum courses.
Contemplate a easy class, Firm, with a couple of attributes:
class Firm:
def __init__(self, identify, trade, num_employees):
self.identify = identify
self.trade = trade
self.num_employees = num_employees
Now, let’s create an occasion of Firm and use dir() to get its attributes:
c = Firm('Dunder Mifflin', 'paper', 15)
print(dir(c))
This can output:
['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'industry', 'num_employees', 'name']
As you’ll be able to see, dir() returns not solely the attributes we outlined (i.e. identify, trade, num_employees), but in addition an inventory of particular strategies (also called dunder strategies) inherent to all Python objects.
Getting their Values
Now that we all know the way to get the attributes of an object, let’s have a look at the way to additionally extract their values. Python gives a built-in operate, getattr(), which permits us to get the worth of a selected attribute.
This is how you need to use getattr():
identify = getattr(c, 'identify')
print(identify)
This can output:
Dunder Mifflin
On this instance, getattr() returns the worth of the identify attribute of the Firm occasion c. If the attribute doesn’t exist, getattr() will elevate an AttributeError. Nevertheless, you’ll be able to present a 3rd argument to getattr(), which will probably be returned if the attribute is just not discovered, thus avoiding the error:
location = getattr(c, 'location', 'Not out there')
print(location)
This can output:
Not out there
On this case, since location is just not an attribute of c, getattr() returns the supplied default worth, ‘Not out there’.
Utilizing __dict__ to get Properties and Values
In Python, each object is supplied with a __dict__ attribute. This built-in attribute is a dictionary that maps the item’s attributes to their respective values. This may be very useful after we wish to extract all properties and values of an object. Let’s have a look at the way it works.
class TestClass:
def __init__(self):
self.attr1 = 'Hi there'
self.attr2 = 'World'
occasion = TestClass()
print(occasion.__dict__)
While you run the above code, it is going to output:
{'attr1': 'Hi there', 'attr2': 'World'}
Be aware: __dict__ doesn’t return strategies of an object, solely the properties and their values.
Formatting Object Attributes into Strings
Typically it’s possible you’ll wish to format the attributes of an object right into a readable string for show or logging functions. Python’s built-in str operate might be overridden in your class to attain this. This is how you are able to do it:
class TestClass:
def __init__(self):
self.attr1 = 'Hi there'
self.attr2 = 'World'
def __str__(self):
return str(self.__dict__)
occasion = TestClass()
print(str(occasion))
While you run the above code, it is going to output:
"{'attr1': 'Hi there', 'attr2': 'World'}"
Using vars() for Attribute Extraction
One other solution to extract attributes from an object in Python is by utilizing the built-in vars() operate. This operate behaves similar to the __dict__ attribute and returns the __dict__ attribute of an object. This is an instance:
class TestClass:
def __init__(self):
self.attr1 = 'Hi there'
self.attr2 = 'World'
occasion = TestClass()
print(vars(occasion))
While you run the above code, it is going to output:
{'attr1': 'Hi there', 'attr2': 'World'}
Be aware: Like __dict__, vars() additionally doesn’t return strategies of an object, solely the properties and their values.
Conclusion
Getting the entire attributes of an object in Python might be achieved in a number of methods. Whether or not you are utilizing dir(), the __dict__ attribute, overriding the str operate, or utilizing the vars() operate, Python gives quite a lot of instruments to extract and manipulate object attributes.
