Tutorial by Examples: i

A module is an importable file containing definitions and statements. A module can be created by creating a .py file. # hello.py def say_hello(): print("Hello!") Functions in a module can be used by importing the module. For modules that you have made, they will need to be in t...

This object, Shape has a property image that depends on numberOfSides and sideWidth. If either one of them is set, than the image has to be recalculated. But recalculation is presumably long, and only needs to be done once if both properties are set, so the Shape provides a way to set both propertie...

In C#, types can define custom Conversion Operators, which allow values to be converted to and from other types using either explicit or implicit casts. For example, consider a class that is meant to represent a JavaScript expression: public class JsExpression { private readonly string expres...

Suppose you have types like the following: interface IThing { } class Thing : IThing { } LINQ allows you to create a projection that changes the compile-time generic type of an IEnumerable<> via the Enumerable.Cast<>() and Enumerable.OfType<>() extension methods. IEnumerabl...

A Closure is a function taken together with an environment. The function is typically an anonymous function defined inside another function. The environment is the lexical scope of the enclosing function (very basic idea of a lexical scope of a function would be the scope that exists between the fun...

Suppose you have many changes in one or more files but from each file you only want to commit some of the changes, you can select the desired changes using: git add -p or git add -p [file] Each of your changes will be displayed individually, and for each change you will be prompted to choose...

A simple context tree (containing some common values that might be request scoped and included in a context) built from Go code like the following: // Pseudo-Go ctx := context.WithValue( context.WithDeadline( context.WithValue(context.Background(), sidKey, sid), time.Now().A...

Matplotlib supports both object-oriented and imperative syntax for plotting. The imperative syntax is intentionally designed to be very close to Matlab syntax. The imperative syntax (sometimes called 'state-machine' syntax) issues a string of commands all of which act on the most recent figure or a...

First, ensure you have imported sessions from flask from flask import session To use session, a Flask application needs a defined SECRET_KEY. app = Flask(__name__) app.secret_key = 'app secret key' Sessions are implemented by default using a cookie signed with the secret key. This ensures t...

props are used to pass data and methods from a parent component to a child component. Interesting things about props They are immutable. They allow us to create reusable components. Basic example class Parent extends React.Component{ doSomething(){ console.log("Parent comp...

When a React component is created, a number of functions are called: If you are using React.createClass (ES5), 5 user defined functions are called If you are using class Component extends React.Component (ES6), 3 user defined functions are called getDefaultProps() (ES5 only) This is the firs...

NSArray *myColors = @[@"Red", @"Green", @"Blue", @"Yellow"]; // Fast enumeration // myColors cannot be modified inside the loop for (NSString *color in myColors) { NSLog(@"Element %@", color); } // Using indices for (NSUInteger i = 0; ...

With automatic reference counting (ARC), the compiler inserts retain, release, and autorelease statements where they are needed, so you don't have to write them yourself. It also writes dealloc methods for you. The sample program from Manual Memory Management looks like this with ARC: @interface M...

Register a production/sandbox account at https://dashboard.stripe.com/register Insert below code into your webpage where you want to have a checkout button. <form action="/charge" method="POST"> <script src="https://checkout.stripe.com/checkout.js" cl...

A word of caution: AsyncTask has many gotcha's apart from the memory leak described here. So be careful with this API, or avoid it altogether if you don't fully understand the implications. There are many alternatives (Thread, EventBus, RxAndroid, etc). One common mistake with AsyncTask is to c...

The installation instructions are available on IIS.net. See this for installing IIS 8.5

The isEqual: method is the only reliable way to determine whether two images contain the same image data. The image objects you create may be different from each other, even when you initialize them with the same cached image data. The only way to determine their equality is to use the isEqual...

Directives, as the name suggests, are direction or instructions for the container to follow when translating a JSP to a servlet. There are 3 directives namely page, include and taglib which you can use in your JSP. Below is a simple example of using page directive: <%@ page isErrorPage="tr...

NOTE: In most cases, it is better to use a UIButton instead of making a UILabel you can tap on. Only use this example, if you are sure, that you don't want to use a UIButton for some reason. Create label Enable user interaction Add UITapGestureRecognizer The key to create a clickable UIL...

Assuming that you have successfully created a JFrame and that Swing has been imported... You can import Swing entirely import javax.Swing.*; or You can import the Swing Components/Frame that you intend to use import javax.Swing.Jframe; import javax.Swing.JButton; Now down to adding the J...