Tutorial by Examples: t

Using the def statement is the most common way to define a function in python. This statement is a so called single clause compound statement with the following syntax: def function_name(parameters): statement(s) function_name is known as the identifier of the function. Since a function def...

Functions can return a value that you can use directly: def give_me_five(): return 5 print(give_me_five()) # Print the returned value # Out: 5 or save the value for later use: num = give_me_five() print(num) # Print the saved returned value # Out: 5 or use the value f...

Decorators augment the behavior of other functions or methods. Any function that takes a function as a parameter and returns an augmented function can be used as a decorator. # This simplest decorator does nothing to the function being decorated. Such # minimal decorators can occasionally be used ...

As mentioned in the introduction, a decorator is a function that can be applied to another function to augment its behavior. The syntactic sugar is equivalent to the following: my_func = decorator(my_func). But what if the decorator was instead a class? The syntax would still work, except that now m...

Decorators normally strip function metadata as they aren't the same. This can cause problems when using meta-programming to dynamically access function metadata. Metadata also includes function's docstrings and its name. functools.wraps makes the decorated function look like the original function b...

A decorator takes just one argument: the function to be decorated. There is no way to pass other arguments. But additional arguments are often desired. The trick is then to make a function which takes arbitrary arguments and returns a decorator. Decorator functions def decoratorfactory(message): ...

The math module contains the math.sqrt()-function that can compute the square root of any number (that can be converted to a float) and the result will always be a float: import math math.sqrt(9) # 3.0 math.sqrt(11.11) # 3.3331666624997918 math.sqrt(Decimal('6.25')) ...

Sometimes you don't want to have your function accessible/stored as a variable. You can create an Immediately Invoked Function Expression (IIFE for short). These are essentially self-executing anonymous functions. They have access to the surrounding scope, but the function itself and any internal va...

When you define a function, it creates a scope. Everything defined within the function is not accessible by code outside the function. Only code within this scope can see the entities defined inside the scope. function foo() { var a = 'hello'; console.log(a); // => 'hello' } consol...

A Promise object represents an operation which has produced or will eventually produce a value. Promises provide a robust way to wrap the (possibly pending) result of asynchronous work, mitigating the problem of deeply nested callbacks (known as "callback hell"). States and control flow ...

The setTimeout() method calls a function or evaluates an expression after a specified number of milliseconds. It is also a trivial way to achieve an asynchronous operation. In this example calling the wait function resolves the promise after the time specified as first argument: function wait(ms) ...

Integers in PHP can be natively specified in base 2 (binary), base 8 (octal), base 10 (decimal), or base 16 (hexadecimal.) $my_decimal = 42; $my_binary = 0b101010; $my_octal = 052; $my_hexadecimal = 0x2a; echo ($my_binary + $my_octal) / 2; // Output is always in decimal: 42 Integers are 3...

A traditional for-loop A traditional for loop has three components: The initialization: executed before the look block is executed the first time The condition: checks a condition every time before the loop block is executed, and quits the loop if false The afterthought: performed every time a...

In addition to the built-in round function, the math module provides the floor, ceil, and trunc functions. x = 1.55 y = -1.55 # round to the nearest integer round(x) # 2 round(y) # -2 # the second argument gives how many decimal places to round to (defaults to 0) round(x, 1) ...

Tk is the standard graphical user interface (GUI) for Ruby. It provides a cross-platform GUI for Ruby programs. Example code: require "tk" TkRoot.new{ title "Hello World!" } Tk.mainloop The result: Step by Step explanation: require "tk" Load the tk package...

import random randint() Returns a random integer between x and y (inclusive): random.randint(x, y) For example getting a random number between 1 and 8: random.randint(1, 8) # Out: 8 randrange() random.randrange has the same syntax as range and unlike random.randint, the last value is no...

git log will display all your commits with the author and hash. This will be shown over multiple lines per commit. (If you wish to show a single line per commit, look at onelineing). Use the q key to exit the log. By default, with no arguments, git log lists the commits made in that reposito...

About Protocols A Protocol specifies initialisers, properties, functions, subscripts and associated types required of a Swift object type (class, struct or enum) conforming to the protocol. In some languages similar ideas for requirement specifications of subsequent objects are known as ‘interfaces...

Protocols may define associated type requirements using the associatedtype keyword: protocol Container { associatedtype Element var count: Int { get } subscript(index: Int) -> Element { get set } } Protocols with associated type requirements can only be used as generic constraints:...

break statement When a break statement executes inside a loop, control flow "breaks" out of the loop immediately: i = 0 while i < 7: print(i) if i == 4: print("Breaking from loop") break i += 1 The loop conditional will not be evaluated a...