generate qr code asp.net mvc Figure 5-2. UML architecture of the translation tool in Visual Basic .NET

Drawer QR Code ISO/IEC18004 in Visual Basic .NET Figure 5-2. UML architecture of the translation tool

Figure 5-2. UML architecture of the translation tool
Encode QR-Code In Visual Basic .NET
Using Barcode encoder for Visual Studio .NET Control to generate, create Quick Response Code image in VS .NET applications.
www.OnBarcode.com
Scanning QR Code In VB.NET
Using Barcode reader for Visual Studio .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
CHAPTER 5 IMPLEMENTING COMPONENT GROUPINGS
Code 3 Of 9 Creation In VB.NET
Using Barcode encoder for Visual Studio .NET Control to generate, create Code-39 image in VS .NET applications.
www.OnBarcode.com
Encode Matrix 2D Barcode In Visual Basic .NET
Using Barcode maker for .NET framework Control to generate, create Matrix 2D Barcode image in VS .NET applications.
www.OnBarcode.com
Taking a quick glance at Figure 5-2, it s obvious that the various references between the individual types are numerous and therefore are creating brittle code. The objective is to clean up the references.
Printing GS1 - 13 In VB.NET
Using Barcode creator for .NET Control to generate, create EAN13 image in .NET framework applications.
www.OnBarcode.com
Generate Data Matrix ECC200 In VB.NET
Using Barcode maker for Visual Studio .NET Control to generate, create DataMatrix image in VS .NET applications.
www.OnBarcode.com
Restructuring to Use the Mediator Pattern
Barcode Generation In VB.NET
Using Barcode generation for Visual Studio .NET Control to generate, create Barcode image in .NET framework applications.
www.OnBarcode.com
Encode ISSN - 10 In Visual Basic .NET
Using Barcode drawer for Visual Studio .NET Control to generate, create ISSN - 10 image in Visual Studio .NET applications.
www.OnBarcode.com
When an application uses references extensively, one solution is to use a middle entity to manage the references and messages to the different entities. The Mediator pattern3 allows you to avoid the problem of requiring types to hold an instance to other types. When implementing GUI applications, you ll use the Mediator pattern extensively. A specialization of the Mediator pattern is the Relational Integrity Mediator pattern.4 Languages like C# aren t meant to effectively manage references; in fact, programming languages do a very poor job of it. In contrast, languages such as Structured Query Language (SQL) do a remarkable job at managing references and constraints. To simplify managing references, a special type of mediator called a relational mediator is used. Like the standard mediator, it s used to manage collections of types that reference other types. More about this specialization of this pattern won t be discussed here, because it s beyond the scope of this book. The Mediator pattern is created by default when you design a GUI. For example, when GUI elements such as buttons are added to a form, they are added as generic controls. The form manages children, and when updates are necessary, the form is responsible for informing the correct control at the correct time. When the child controls need to update other controls, they ask the form, which then gets the reference for the child. The child doesn t need to hold any references and can always ask for them dynamically. The class TranslationTextBox can be simplified using the Mediator pattern by calling the parent form and asking for the textbox that needs to be updated, as in the following source code: public class TranslationTextBox: System.Windows.Forms.TextBox { private ITranslationServices _translation; public TranslationTextBox() { } protected override void OnTextChanged( EventArgs e) { Form parent; TextBox othertextbox; parent = this.Parent as Form; othertextbox = parent.Controls[ "textbox2"] as TextBox; othertextbox.Text = _translation.Translate(this.Text); } public void AssignTranslation(ITranslationServices translation) { _translation = translation; } }
Reading QR Code In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
Read Quick Response Code In C#.NET
Using Barcode decoder for .NET framework Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
3. Erich Gamma et al., Design Patterns: Elements of Reusable Object-Oriented Software (Boston: Addison-Wesley, 1995), p. 273. 4. Steven John Metsker, Design Patterns in C# (Boston: Addison-Wesley, 2004), p. 115.
Barcode Creation In C#
Using Barcode maker for .NET framework Control to generate, create Barcode image in .NET applications.
www.OnBarcode.com
Generating Linear Barcode In C#
Using Barcode creation for Visual Studio .NET Control to generate, create Linear 1D Barcode image in Visual Studio .NET applications.
www.OnBarcode.com
CHAPTER 5 IMPLEMENTING COMPONENT GROUPINGS
Encoding EAN-13 In None
Using Barcode maker for Font Control to generate, create EAN13 image in Font applications.
www.OnBarcode.com
UCC - 12 Creation In Java
Using Barcode drawer for Java Control to generate, create GS1 128 image in Java applications.
www.OnBarcode.com
Comparing this implementation of TranslationTextBox to the previous definition, notice how the data member _textbox isn t necessary. The constructor of TranslationTextBox is modified to not need any parameters. The form uses the Mediator pattern, and therefore if the TranslationTextBox needs the output textbox, it just asks the form. In the OnTextChanged method, the form is retrieved using the this.Parent property. Then the control is retrieved using the indexer parent.Controls[ "textbox2"]. The returned control is typecast to type TextBox. Twice types have been typecast (for example, as Form and as TextBox) to general .NET GUI-based types, and twice the typecast could have resulted in a cast exception. A cast exception didn t occur because the TranslationTextBox knew what it was asking for. This illustrates one aspect of the Mediator pattern: the individual clients managed by the mediator know about other clients in base type terms and know their identity. In the example, the identity was textbox2, but usually this would be an identifier associated with the functionality of the instance. OnTextChanged is a classical implementation of the Mediator pattern because the child control is letting the parent container manage the references of other child controls. Then when the child control needs to access another control to display a message or perform some action, the parent container is asked. In terms of the Mediator pattern, the architecture would now appear similar to Figure 5-3.
QR Code 2d Barcode Printer In Java
Using Barcode creation for BIRT reports Control to generate, create Denso QR Bar Code image in Eclipse BIRT applications.
www.OnBarcode.com
Universal Product Code Version A Printer In Java
Using Barcode drawer for BIRT reports Control to generate, create UPC-A image in BIRT reports applications.
www.OnBarcode.com
Figure 5-3. UML architecture of translation tool using the Mediator pattern Notice the incremental improvement in Figure 5-3 in terms of a more organized and logical architecture. The referencing of all types by all types is gone and replaced with the referencing of types when necessary. The Mediator pattern is implemented by the types Form, BasicForm, TranslationTextBox, and TextBox. The types Form and BasicForm are the Mediator and ConcreteMediator, respectively. The TranslationTextBox doesn t use or know about the ConcreteMediator because that would violate the Mediator pattern and the separation of interface from implementation. The types TextBox and TranslationTextBox are colleagues and concrete colleagues, respectively. The Mediator pattern is a collection container that has references to all of its children as colleagues. If one concrete colleague needs to reference another concrete colleague, it asks the
QR Code 2d Barcode Scanner In .NET
Using Barcode scanner for Visual Studio .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
Draw Barcode In Objective-C
Using Barcode encoder for iPhone Control to generate, create Barcode image in iPhone applications.
www.OnBarcode.com
Reading Barcode In VB.NET
Using Barcode Control SDK for VS .NET Control to generate, create, read, scan barcode image in .NET framework applications.
www.OnBarcode.com
Encoding GS1 DataBar Truncated In Visual Studio .NET
Using Barcode creation for VS .NET Control to generate, create GS1 DataBar Expanded image in .NET applications.
www.OnBarcode.com
Copyright © OnBarcode.com . All rights reserved.