Python Data Structures and Algorithms

Functions as first class objects

In Python, it is not only data types that are treated as objects. Both functions and classes are what are known as first class objects, allowing them to be manipulated in the same ways as built-in data types. By definition, first class objects are:

• Created at runtime
• Assigned as a variable or in a data structure
• Passed as an argument to a function
• Returned as the result of a function

In Python, the term first class object is a bit of a misnomer since it implies some sort of hierarchy, whereas all Python objects are essentially first class.

To have a look at how this works, let's define a simple function:

    def greeting(language):     if language== 'eng':              return 'hello world'        if language  == 'fr'  return 'Bonjour ...