*args vs **kwargs
*args captures extra positional arguments and **kwargs captures extra keyword arguments.
- args becomes tuple
- kwargs becomes dict
- Useful for flexible APIs
*args vs **kwargs
Tagged with functions
9 cards
Default arguments and mutable default values
Default argument values are evaluated once at function definition time, which makes mutable defaults a common bug source.
- Immutable defaults are safer
- Use `None` as a sentinel
- Mutable defaults persist across calls
Default arguments and mutable default values
First-class functions, higher-order functions, lambda functions, and closures
Functions are first-class values in Python, so you can pass them around, return them, and build closures or higher-order helpers.
- Lambda is for small anonymous functions
- Closures capture enclosing state
- Higher-order functions accept or return callables
First-class functions, higher-order functions, lambda functions, and closures
Positional, keyword, keyword-only, and positional-only arguments
Python lets you control how callers pass arguments so APIs can be both flexible and explicit.
- Positional-only uses `/`
- Keyword-only uses `*`
- Signature design affects readability
Positional, keyword, keyword-only, and positional-only arguments
Return values, multiple return values, function annotations, and docstrings
Python functions can return any object, often pack multiple results into a tuple, and may document intent through annotations and docstrings.
- Multiple returns are tuple packing
- Annotations describe intent, not runtime enforcement by default
- Docstrings explain usage and behavior
Return values, multiple return values, function annotations, and docstrings
What is a decorator?
A decorator wraps another callable to add behavior without changing the original function body.
- Starts with a callable
- Usually returns a wrapper
- Common for logging, auth, caching
What is a decorator?
Function declarations, function expressions, arrow functions, default parameters, rest parameters, callbacks, higher-order functions, first-class functions, IIFE, and pure functions
JavaScript functions are first-class values, which is why callbacks, higher-order utilities, and different function forms all matter.
- Declarations and expressions behave differently
- Arrow functions change `this` behavior
- Pure functions avoid hidden side effects
Function declarations, function expressions, arrow functions, default parameters, rest parameters, callbacks, higher-order functions, first-class functions, IIFE, and pure functions
Recursion, memoization, currying, debounce, and throttle in JavaScript
These patterns solve different problems: recursion for self-referential logic, memoization for caching, currying for partial application, and debounce or throttle for rate control.
- Memoization trades memory for repeated-speed gains
- Debounce waits for quiet time
- Throttle limits call frequency
Recursion, memoization, currying, debounce, and throttle in JavaScript
The this keyword in global scope, methods, regular functions, arrow functions, and call/apply/bind
`this` depends on how a function is called, and `call`, `apply`, and `bind` let you control that context explicitly.
- Arrow functions do not create their own `this`
- Method calls bind `this` to the receiver
- `bind` returns a new function
The this keyword in global scope, methods, regular functions, arrow functions, and call/apply/bind