Tutorial by Examples: l

Intent: Define an interface for creating an object, but let sub classes decide which class to instantiate. Factory Method lets a class defer instantiation to sub classes. UML diagram: Product: It defines an interface of the objects the Factory method creates. ConcreteProduct: Implements Produc...

The Builder pattern allows you to create an instance of a class with many optional variables in an easy to read way. Consider the following code: public class Computer { public GraphicsCard graphicsCard; public Monitor[] monitors; public Processor processor; public Memory[] r...

Assume you have a application that administers rooms. Assume further that your application operates on a per client basis (tenant). You have several clients. So your database will contain one table for clients, and one for rooms. Now, every client has N rooms. This should mean that you have...

Another way to hide admin bar is to add if ( !current_user_can( 'manage_options' ) ) { add_filter( 'show_admin_bar', '__return_false' , 1000 ); } The users who don't have privileges to access Settings page, won't be able to see the admin bar.

Input.acceleration is used to read the accelerometer sensor. It returns Vector3 as a result which contains x,y and z axis values in 3D space. void Update() { Vector3 acclerometerValue = rawAccelValue(); Debug.Log("X: " + acclerometerValue.x + " Y: " + acclerometerV...

You can use the DataExtension mechanism to add extra database fields to an existing DataObject: class MyMemberExtension extends DataExtension { private static $db = [ 'HairColour' => 'Varchar' ]; } And apply the extension: # File: mysite/_config/app.yml Member: exten...

BigInteger supports the binary logic operations that are available to Number types as well. As with all operations they are implemented by calling a method. Binary Or: BigInteger val1 = new BigInteger("10"); BigInteger val2 = new BigInteger("9"); val1.or(val2); Output:...

Headers may be used to declare globally used read-only resources, like string tables for example. Declare those in a separate header which gets included by any file ("Translation Unit") which wants to make use of them. It's handy to use the same header to declare a related enumeration to ...

SELECT * FROM customers WHERE id IN ( SELECT DISTINCT customer_id FROM orders ); The above will give you all the customers that have orders in the system.

Classes provide a way of creating your own types within the .NET framework. Within a class definition you may include the following: Fields Properties Methods Constructors Events To declare a class you use the following syntax: Public Class Vehicle End Class Other .NET types can...

If classes share common functionality you can group this in a base or abstract class. Abstract classes can contain partial or no implementation at all and allow the derived type to override the base implementation. Abstract classes within VisualBasic.NET must be declared as MustInherit and cannot ...

You can provide help for message box in different ways. You can configure a MessageBox to show a Help button or not. Also you can configure MessageBox in a way that when the user requests for help by click on Help button or by pressing F1, it show a CHM file or navigate to a URL or perform a custom ...

You can provide help for OpenFileDialog, SaveFileDialog and ColorDialog. To do so set ShowHelp property of dialog to true and handle HelpRequest event for dialog: void openFileDialog1_HelpRequest(object sender, EventArgs e) { //Perform custom action Help.ShowHelp(this, "Http://examp...

When a user press F1 on a control or click on Help button of form (?) and then clicks on a control the HelpRequested event will be raised. You can handle this event to provide custom action when user requests help for controls or form. The HelpRequested supports bubble up mechanism. It fires for y...

You can use Help class in code, to provide these kinds of help: Show a help pop-up for a control Open a CHM file based on context (Show table of content, Show a keyword or index, show a topic) Navigate to a URL using default browser Show Help pop-up window You can use Help.ShowPopup to disp...

You can show a Help Button at title-bar of a Form. To do so, you should: Set HelpButton property of form to true. Set MinimizeBox and MaximizeBox to false. Then a help button will appear on title-bar of Form: Also when you click on Help button, the cursor will be changed to a ? cursor: ...

If you have a Form with MinimizeBox and MaximizeBox set to true, then you can not show Help button on title-bar of Form and will lose the feature of click on help button to convert it to help cursor to be able to click on controls to show help. You can make a menu item on MenuStrip act like standar...

You can detect when a user Clicked on a HelpButton on title-bar of form by handling HelpButtonClicked. You can let the event continue or cancel it by setting Cancel property of its event args to true. private void Form1_HelpButtonClicked(object sender, CancelEventArgs e) { e.Cancel = true; ...

The protected internal keyword marks field, methods, properties and nested classes for use inside the same assembly or derived classes in another assembly: Assembly 1 public class Foo { public string MyPublicProperty { get; set; } protected internal string MyProtectedInternalPropert...

SELECT * FROM Cars WHERE status IN ( 'Waiting', 'Working' ) This is semantically equivalent to SELECT * FROM Cars WHERE ( status = 'Waiting' OR status = 'Working' ) i.e. value IN ( <value list> ) is a shorthand for disjunction (logical OR).