Tutorial by Examples: io

Detailed instructions on getting concurrency set up or installed.

Use the makemigrations --name <your_migration_name> option to allow naming the migrations(s) instead of using a generated name. python manage.py makemigrations --name <your_migration_name> <app_name>

After successfully installing Xamarin as described in the first example, it's time to launch the first sample application. Step 1: Creating a new Project. In Visual Studio, choose New -> Project -> Visual C# -> Cross-Platform -> Blank App (Xamarin.Forms Portable) Name the app "He...

In order for a program to react to a certain signal, other than using default action, custom signal handler can be installed using sigaction. sigaction receives three arguments - signal to act on, pointer to sigaction_t structure which, if not NULL, is describing new behaviour and pointer to sigacti...

SELECT DATE('2003-12-31 01:02:03'); The output will be: 2003-12-31

Least squares is a standard approach to problems with more equations than unknowns, also known as overdetermined systems. Consider the four equations: x0 + 2 * x1 + x2 = 4 x0 + x1 + 2 * x2 = 3 2 * x0 + x1 + x2 = 5 x0 + x1 + x2 = 4 We can express this as a matrix multiplication A * x = b: A ...

CREATE TABLE foo ( ... name CHARACTER SET utf8mb4 ... );

Vital to using character sets is to tell the MySQL-server what encoding the client's bytes are. Here is one way: SET NAMES utf8mb4; Each language (PHP, Python, Java, ...) has its own way the it usually preferable to SET NAMES. For example: SET NAMES utf8mb4, together with a column declared CH...

There are dozens of character sets with hundreds of collations. (A given collation belongs to only one character set.) See the output of SHOW COLLATION;. There are usually only 4 CHARACTER SETs that matter: ascii -- basic 7-bit codes. latin1 -- ascii, plus most characters needed for Western Eur...

Getting zsh zsh is available on many UNIX-like platforms via their built-in package management systems. On the Debian and Ubuntu Linux distributions, zsh is available in the default package repositories and can be installed using: $ sudo apt-get install zsh # or, on newer Ubuntu distributions $ ...

module.exports.routes = { 'GET /foo': 'FooController.index', 'GET /foo/new': 'FooController.new', 'POST /foo/create': 'FooController.create', 'GET /foo/:id/edit': 'FooController.edit', 'PUT /foo/:id/update': 'FooController.update', 'GET /foo/:id': 'FooController.show', ...

The yield keyword allows lazy-evaluation of the collection. Forcibly loading the whole collection into memory is called eager evaluation. The following code shows this: IEnumerable<int> myMethod() { for(int i=0; i <= 8675309; i++) { yield return i; } } ... // ...

Consider using Extension Methods as Functions which wrap other code, here's a great example that uses both a static method and and extension method to wrap the Try Catch construct. Make your code Bullet Proof... using System; using System.Diagnostics; namespace Samples { /// <summary&g...

Many database configurations require authentication (in the form of a username and password) before you can query the database. You can supply these using the username and password attributes. Note: the username and password can also be configured against the datasource in the ColdFusion Administra...

Virtual Methods are methods in Java that are non-static and without the keyword Final in front. All methods by default are virtual in Java. Virtual Methods play important roles in Polymorphism because children classes in Java can override their parent classes' methods if the function being overriden...

C.I.A.s are intended as a simple way of getting attributes from whatever is calling the targeted method. There is really only 1 way to use them and there are only 3 attributes. Example: //This is the "calling method": the method that is calling the target method public void doProcess() ...

Example showing how to create Guis using functions instead of labels. Gui, Add, Button, gCtrlEvent vButton1, Button 1 Gui, Add, Button, gCtrlEvent vButton2, Button 2 Gui, Add, Button, gGoButton, Go Button Gui, Add, Edit, vEditField, Example text Gui, Show,, Functions instead of labels CtrlEv...

Lambda expressions are similar to anonymous functions in other languages. Lambda expressions are open formulas which also specify variables which are to be bound. Evaluation (finding the value of a function call) is then achieved by substituting the bound variables in the lambda expression's body, ...

Function scope is the special scope for labels. This is due to their unusual property. A label is visible through the entire function it is defined and one can jump (using instruction gotolabel) to it from any point in the same function. While not useful, the following example illustrate the point: ...

Function-like macros are similar to inline functions, these are useful in some cases, such as temporary debug log: #ifdef DEBUG # define LOGFILENAME "/tmp/logfile.log" # define LOG(str) do { \ FILE *fp = fopen(LOGFILENAME, "a"); \ ...