The __qualname__ attribute means qualified name in Python. It gives you a dotted path to the name of the target object.
Using __qualname__ is useful with nested structures, such as when you have a method inside a class.
For example:
class Example:
def something():
pass
print(Example.something.__qualname__)
The result of this is a full path to the attribute:
Example.something
__qualname__ vs __name__ in Python
In Python, there is another similar attribute called __name__. This attribute also shows the naming information about an object.
For example:
class Example:
pass
print(Example.__name__)
Output:
Example
If you compare this to the __qualname__ attribute:
class Example:
pass
print(Example.__qualname__)
Output:
Example
You see that both attributes gave the same result.
But what is the difference between the two?
With nested structures, the __qualname__ returns a path to the object. The __name__ attribute does not.
For example:
class Example:
def something():
pass
print(Example.something.__name__)
print(Example.something.__qualname__)
Output:
something Example.something
Here the __qualname__ returns the path to something method inside the Example class. The __name__ attribute does not do this as it merely knows the name of the method.
Using __qualname__ is useful if you have a function and a method with the same names. Using __qualname__ you are able to see the difference between the method and the function based on the path it returns.
def something():
pass
class Example:
def something():
pass
print(something.__qualname__)
print(Example.something.__qualname__)
Output:
something Example.something
But using only the __name__ attribute you would not be able to tell the difference. This is because the __name__ does not return a full path to the object.
For example:
def something():
pass
class Example:
def something():
pass
print(something.__name__)
print(Example.something.__name__)
Output:
something something
Another useful feature of __qualname__ is it can be called in the class. You can access the name of the class from within even if you do not have an __init__ method specified.
For example:
class Example:
print(__qualname__)
Output:
Example
Conclusion
Today you learned what is the __qualname__ attribute in Python.
To recap, the __qualname__ attribute returns a complete path to an object. This is useful information when dealing with nested structures, such as when you have a class with a method.