GeeksforGeeks
geeksforgeeks.org › python › default-arguments-in-python
Default arguments in Python - GeeksforGeeks
In Python, functions can have default arguments, which are parameters with predefined values.
Published: March 18, 2026
W3Schools
w3schools.com › python › gloss_python_function_default_parameter.asp
Python Default Parameter Value
Python Examples Python Compiler Python Exercises Python Quiz Python Challenges Python Practice Problems Python Server Python Syllabus Python Study Plan Python Interview Q&A Python Training ... The following example shows how to use a default parameter value. If we call the function without argument, it uses the default value:
Today I re-learned: Python function default arguments are retained between executions
I had to find this out the hard way :/ P.s. I am a little rusty on python, but if you want a mutable default value (say a list) you can make the default None then inside the function you would reassign the variable if it's None. More on reddit.com
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January 20, 2023Python: default value of function as a function argument - Stack Overflow
def myF(a, b): return a*b-2*b Let's say that I want a default value for b to be a-1: def myF(a, b=a-1): return a*b-2*b gets the error message: NameError: name 'a' is not defined I can us... More on stackoverflow.com
In Python, can I specify a function argument's default in terms of other arguments? - Stack Overflow
Suppose I have a python function that takes two arguments, but I want the second arg to be optional, with the default being whatever was passed as the first argument. So, I want to do something lik... More on stackoverflow.com
What the default arguments are?
Some sources point out that arguments might be default. But they are not clear in what these arguments are. Sometimes it looks like the default arguments are mismatched with keyword-only parameters or positional and keyw… More on discuss.python.org
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October 3, 202307:28
Understanding Default Arguments in Python (For Beginners) - YouTube
02:46
Default Parameters | Python Programming Ep. 23 - YouTube
Functions in Python | Default Parameters | Scope of Variables ...
Python Default Values for Positional Arguments - YouTube
00:58
Weird Python: Mutable Default Arguments - YouTube
06:07
Python default arguments are awesome! 👍 - YouTube
Codecademy
codecademy.com › learn › learn-intermediate-python-3 › modules › int-python-function-arguments › cheatsheet
Learn Intermediate Python 3: Function Arguments Cheatsheet | Codecademy
If the function is invoked without a value for a specific argument, the default value will be used. ... In Python, a default parameter is defined with a fallback value as a default argument.
Home and Learn
homeandlearn.uk › python-functions-defaults.html
Python Default function values
You can set up your Python functions to have default values. Between the round brackets of your function definition, come up with a variable name then type an equals sign.After the equals sign, type a value for your variable. For example, suppose we want our function from the previous lesson ...
Boot.dev
boot.dev › lessons › 3963019a-a8ce-45c0-b988-3e6e4121aa36
Learn Python for Beginners: Default Values | Boot.dev
You can specify a default value for a function parameter, which is useful when a function has parameters that are "optional".
Python Tutorial
pythontutorial.net › home › python basics › python default parameters
Python Default Parameters
October 5, 2020 - In this syntax, you specify default values (value2, value3, …) for each parameter using the assignment operator (=). When you call a function and pass an argument to the parameter that has a default value, the function will use that argument instead of the default value.
Reddit
reddit.com › r/python › today i re-learned: python function default arguments are retained between executions
r/Python on Reddit: Today I re-learned: Python function default arguments are retained between executions
January 20, 2023 - P.s. I am a little rusty on python, but if you want a · mutable default value (say a list) you can make the · default None then inside the function you would reassign the variable if it's None.
Python Guides
pythonguides.com › use-default-function-arguments-in-python
How to Use Default Function Arguments in Python?
March 19, 2025 - In Python, you can assign default values to function parameters. If an argument is not provided when the function is called, the parameter will automatically take on the specified default value.
The Hitchhiker's Guide to Python
docs.python-guide.org › writing › gotchas
Common Gotchas — The Hitchhiker's Guide to Python
A new list is created once when the function is defined, and the same list is used in each successive call. Python’s default arguments are evaluated once when the function is defined, not each time the function is called (like it is in say, Ruby).
TutorialsPoint
tutorialspoint.com › What-are-default-arguments-in-python
Python - Default Arguments
June 12, 2020 - Default arguments in Python are the function arguments that will be used if no arguments are passed to the function call.
Top answer 1 of 3
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You can do the following:
def myF(a, b=None):
if b is None:
b = a - 1
return a * b - 2 * b
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If you need to have the value of b be a function of a, but you might need that function to change, you can set the default value of b to be a lambda function and then check if b is callable in the function block.
def myF(a, b=lambda a: a-1):
if callable(b):
b = b(a)
return a * b - 2 * b
This allows you to set a different function for b on the fly as well.
# pass b as an integer
myF(1, 1)
# returns: -1
# use default function for b
myF(4)
# returns: 6
# set b to be 2*a + 1
myF(3, lambda a: 2*a+1)
# returns: 7
Medium
medium.com › python4you › python-functions-defaults-explained-ee962c7c6f7a
Python Functions Defaults Explained | by Artem Rys | python4you | Medium
April 21, 2019 - The empty list that we see from the f.__defaults__ result is basically the l variable in the function code.
Top answer 1 of 4
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As @Ignacio says, you can't do this. In your latter example, you might have a situation where None is a valid value for arg2. If this is the case, you can use a sentinel value:
sentinel = object()
def myfunc(arg1, arg2=sentinel):
if arg2 is sentinel:
arg2 = arg1
print (arg1, arg2)
myfunc("foo") # Prints 'foo foo'
myfunc("foo", None) # Prints 'foo None'
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Not really. The other argument names don't exist until the function is actually entered.
InterServer
interserver.net › home › python › how to use default arguments in python for clean and flexible code
How to Use Default Arguments in Python for Clean and Flexible Code - Interserver Tips
April 23, 2026 - This helps make functions flexible and easier to use. In Python, you can set a default value by using an equal sign = after the parameter name.
YouTube
youtube.com › watch
Python default arguments are awesome! 👍 - YouTube
#python #tutorial #course 00:00:00 default arguments00:03:16 exercise# ----- EXAMPLE -----def net_price(list_price, discount=0, tax=0.05): return list_pric...
Published: November 29, 2022
Python.org
discuss.python.org › python help
What the default arguments are? - Python Help - Discussions on Python.org
October 3, 2023 - Some sources point out that arguments might be default. But they are not clear in what these arguments are. Sometimes it looks like the default arguments are mismatched with keyword-only parameters or positional and keyword parameters. E.g.: def greet(name, greeting="Hello"): print(f"{greeting}, {name}!") greet("Alice") greet("Bob", "Hi") One source even suggests that the value of greeting (i.e. “Hello”) is that default argument.
Medium
medium.com › @nebiyuelias1 › be-careful-when-using-default-arguments-in-python-fd92df94efee
Be careful when using default arguments in Python | by Nebiyu Elias | Medium
December 16, 2021 - The doc is saying if you use a mutable object as a default argument it will be evaluated only once. So in the previous example: When the function is defined for the first time(I am not saying when it’s called, I’m saying when it’s defined), Python evaluates the default argument and accumulates(caches) it somehow.
Python
docs.python.org › 2.0 › ref › function.html
7.5 Function definitions
When one or more top-level parameters have the form parameter = expression, the function is said to have ``default parameter values.'' For a parameter with a default value, the corresponding argument may be omitted from a call, in which case the parameter's default value is substituted.
Python
docs.python.org › 3 › builtins › functions.html
Built-in Functions — Python 3.14.8 documentation
If the named attribute does not exist, default is returned if provided, otherwise AttributeError is raised. name need not be a Python identifier (see setattr()). ... Since private name mangling happens at compilation time, one must manually mangle a private attribute’s (attributes with two leading underscores) name in order to retrieve it with getattr(). ... Return the dictionary implementing the current module namespace. For code within functions, this is set when the function is defined and remains the same regardless of where the function is called.
AlgoMaster
algomaster.io › home › python › default & keyword arguments
Default Arguments | Python | AlgoMaster.io
June 6, 2026 - A default argument is a value Python supplies when the caller doesn't pass one. They make function signatures shorter at the call site, give you a sensible fallback for optional knobs, and let you add new parameters to a function without breaking ...