How to refer to the null object in Python? Many programmers get worried about “null” in Python, especially when switched from other programming languages. It is a fact that Python doesn’t have the keyword null. However, there are other ways where we can refer to the null object. In this article, we will learn how to refer to a null object in Python.
1. Null Object in Python
Before we discuss null in Python, let’s understand why we need the concept of “null”. In Computer programming, we use the concept of null as a special value representing the absence or the lack of a value.
You can use “null” as a placeholder or a default value to indicate that a variable or a parameter has not been assigned a value yet, or that a function or method does not return a value. It is a good starting point to assign “null” as an empty value to an identifier and then reassign an actual value.
Many languages use the built-in keyword “null” to define a null object. In Python, null is represented by the keyword “
None“. It is considered a built-in constant that represents the null value. It is an object of the type “
NoneType” and can be assigned to variables or used as a return value for functions and methods.
# Assign a variable None or null Value my_var = None
Now you can check the type of the “my_var” to see if it is referring to a null object or not. See the following code:
# Assign Null to a variable my_var = None # Check the type print(type(my_var)) # Output: # class 'NoneType'
2. Null as the Default Parameter
None is often used as a default parameter value to indicate the absence of a value or to provide a placeholder value when no argument is provided for a parameter. This allows for more flexible function definitions and provides a way to handle optional arguments.
Using None as a default parameter is especially useful when you have optional arguments that the caller may or may not provide. It allows you to define a function with sensible default behavior while still allowing the caller to override those defaults if needed.
def say_hi(name=None): if name is None: print("hi, stranger!") else: print("hi, " + name + "!") say_hi() # Output: hi, stranger! say_hi("Ali") # Output: hi, Ali!
3. Referring to Null in Equality
Most of the time we use the
== signs for equality and
!= for inequality. In Python, there is also an alternative to use the identity operators
is not when comparing a variable with
None, rather than using the equality operators
The identity operators specifically check if two objects refer to the same memory location, whereas the equality operators check if the values of the objects are equal.
x = None # Using identity operators if x is None: print("x is None") if x is not None: print("x is not None") # Using equality operators if x == None: print("x == None") if x != None: print("x != None")
Using the identity operators can be faster and more efficient than using the equality operators, as it may not require type conversion or other processing.
The demonstration lies in the fact that
x is None is similar to
id(x)==id(x) . While
x==None is similar to
4. The Singleton Nature of Python Null (None)
Python None is considered a singleton, meaning any further attempts to instantiate the NoneType class will return the same None object. When encountering error messages mentioning NoneType, it simply refers to the None object being used in a way that it cannot fulfill.
# Checking None's uniqueness using id() mem=id(None) print(mem) # Output: # 140712405712088 my_none = None print(id(my_none)) # Output: # 140712405712088 another_none = None print(id(another_none)) # Output: # 140712405712088
In the above code, you see that
None is a unique object with a specific identity. The
id() function returns the unique identifier assigned to an object. From the output you can see that multiple assignments of
None to different variables yield the same unique identifier, indicating that they all point to the same
5. “None” – Create a Null Object in Python
As mentioned above the keyword “None” allows you to create a null object, providing a means for initialization to the null reference.
When a variable has not been assigned a valid value, you can use the keyword
None to indicate that this object has a null value. You can use this can when dealing with optional parameters or cases where a value may be missing.
See the below example:
empty = None # Checking if the object is None if empty is None: print("The object is None") else: print("The object is not None") # Checking the type of the object print(type(empty)) # Output: # The object is None # class 'NoneType'
6. “None” as a Binary (True or False)
You can use the
None object as a binary value, where it can be considered either True or False in specific contexts. We can use this behavior when dealing with conditions or boolean evaluations.
When evaluated in a boolean context, None is considered False. This means that if None is used in a condition or as part of an expression that expects a boolean value, it will be treated as False. On the other hand, any non-None object is considered True in a boolean context.
def check_value(value): if value: print(False) else: print(True) # Example 1: Using a non-None value check_value("Hello") # Output: False # Example 2: Using None check_value(None) # Output: True
7. Summary and Conclusion
In this article, we have learned how to refer to null object in Python. In Python, null is represented by the keyword “None”. It is considered a built-in constant that represents the null value. It is an object of the type “NoneType” and can be assigned to variables or used as a return value for functions and methods. I hope this article was helpful, if you have any questions please leave them in the comment section.