Quark's Outlines: Python User-defined Functions

Quark’s Outlines: Python User-Defined Functions Overview, Historical Timeline, Problems & Solutions An Overview of Python User-Defined Functions What is a Python user-defined function? You can define your own function in Python using the def keyword. A Python user-defined function is made when you write a def block in your code. When Python runs this block, it creates a function object. A function object has special parts. These include its name, its list of default values, and its code. It also keeps a link to the global names from the file where it was made. You can use this object to call the function later with any valid input. Python lets you create named function objects with the def keyword. def greet ( name = " friend " ): return " Hello, " + name print ( greet ()) print ( greet ( " Mike " )) # prints: # Hello, friend # Hello, Mike The function greet is now a user-defined function. Python stores its name, code, and default values for later use. What are the special parts of a Python function? A Python function holds many facts about itself. These are called attributes. For example, __name__ holds the function name. __defaults__ is a tuple of default values. __globals__ holds the global names it can see. __code__ is a special object that stores the function’s bytecode. Python functions store their details in special attributes. def square ( x = 2 ): return x * x print ( square . __name__ ) print ( square . __defaults__ ) print ( square . __code__ . co_varnames ) # prints: # square # (2,) # ('x',) These parts let Python understand and run your function later. A Historical Timeline of Python User-Defined Functions Where do Python’s user-defined functions come from? User-defined functions in Python build on ideas from earlier languages. They let you name blocks of code and reuse them. Over time, Python added new parts to function objects—like closures, default values, and metadata—to make them more powerful. People designed ways to name and reuse logic 1958 — Fu