Tutorial by Examples: v

Python 3.x3.0 Python 3 added a new keyword called nonlocal. The nonlocal keyword adds a scope override to the inner scope. You can read all about it in PEP 3104. This is best illustrated with a couple of code examples. One of the most common examples is to create function that can increment: def c...

To iterate all files, including in sub directories, use os.walk: import os for root, folders, files in os.walk(root_dir): for filename in files: print root, filename root_dir can be "." to start from current directory, or any other path to start from. Python 3.x3.5 If ...

vimtutor is an interactive tutorial covering the most basic aspects of text editing. On UNIX-like system, you can start the tutorial with: $ vimtutor On Windows, “Vim tutor” can be found in the “Vim 7.x” directory under “All Programs” in the Windows menu. See :help vimtutor for further details...

You can create a TCP server using the socketserver library. Here's a simple echo server. Server side from sockerserver import BaseRequestHandler, TCPServer class EchoHandler(BaseRequestHandler): def handle(self): print('connection from:', self.client_address) while True:...

A UDP server is easily created using the socketserver library. a simple time server: import time from socketserver import BaseRequestHandler, UDPServer class CtimeHandler(BaseRequestHandler): def handle(self): print('connection from: ', self.client_address) # Get message and cli...

Inventory is the Ansible way to track all the systems in your infrastructure. Here is a simple inventory file containing a single system and the login credentials for Ansible. [targethost] 192.168.1.1 ansible_user=mrtuovinen ansible_ssh_pass=PassW0rd

[targethost] 192.168.1.1 ansible_user=mrtuovinen ssh_private_key_file=~/.ssh/custom_key

[targethost] 192.168.1.1 ansible_user=mrtuovinen ansible_port=2222

In Fortran functions and subroutines need to be explicitly declared as recursive, if they are to call themselves again, directly or indirectly. Thus, a recursive implementation of the Fibonacci series could look like this: recursive function fibonacci(term) result(fibo) integer, intent(in) :: te...

It is possible to detect whether an operator or function can be called on a type. To test if a class has an overload of std::hash, one can do this: #include <functional> // for std::hash #include <type_traits> // for std::false_type and std::true_type #include <utility> // for s...

You can validate any object, even plain ruby. class User include ActiveModel::Validations attr_reader :name, :age def initialize(name, age) @name = name @age = age end validates :name, presence: true validates :age, numericality: { only_integer: true, greater_than...

Swift func createCollectionView() { let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout() let collectionView = UICollectionView(frame: CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height), collectionViewLayout: layout) collectionView.dataSource = sel...

// MARK: - UICollectionViewDelegateFlowLayout extension ViewController: UICollectionViewDelegateFlowLayout { func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize { return ...

You can use an initializer to set default property values: struct Example { var upvotes: Int init() { upvotes = 42 } } let myExample = Example() // call the initializer print(myExample.upvotes) // prints: 42 Or, specify default property values as a part of the property...

Euler angles are "degree angles" like 90, 180, 45, 30 degrees. Quaternions differ from Euler angles in that they represent a point on a Unit Sphere (the radius is 1 unit). You can think of this sphere as a 3D version of the Unit circle you learn in trigonometry. Quaternions differ from Eu...

uvloop is an implementation for the asyncio.AbstractEventLoop based on libuv (Used by nodejs). It is compliant with 99% of asyncio features and is much faster than the traditional asyncio.EventLoop. uvloop is currently not available on Windows, install it with pip install uvloop. import asyncio i...

virtual and override The virtual keyword allows a method, property, indexer or event to be overridden by derived classes and present polymorphic behavior. (Members are non-virtual by default in C#) public class BaseClass { public virtual void Foo() { Console.WriteLine("Foo...

A recursive function is simply a function, that would call itself. function factorial (n) { if (n <= 1) { return 1; } return n * factorial(n - 1); } The above function shows a basic example of how to perform a recursive function to return a factorial. Another...

First of all, we need to add our first Fragment at the beginning, we should do it in the onCreate() method of our Activity: if (null == savedInstanceState) { getSupportFragmentManager().beginTransaction() .addToBackStack("fragmentA") .replace(R.id.container, FragmentA.n...

Python 2.x2.7 "1deadbeef3".decode('hex') # Out: '\x1d\xea\xdb\xee\xf3' '\x1d\xea\xdb\xee\xf3'.encode('hex') # Out: 1deadbeef3 Python 3.x3.0 "1deadbeef3".decode('hex') # Traceback (most recent call last): # File "<stdin>", line 1, in <module> ...