birt barcode generator Refactoring Duplicated Code Using the Template Method in VB.NET

Painting QR in VB.NET Refactoring Duplicated Code Using the Template Method

Refactoring Duplicated Code Using the Template Method
Generate Denso QR Bar Code In VB.NET
Using Barcode generator for VS .NET Control to generate, create QR image in .NET applications.
www.OnBarcode.com
QR-Code Decoder In Visual Basic .NET
Using Barcode scanner for .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Duplication behavior needs to be stopped whenever possible. It s destructive and causes problems in the long term. Oddly enough, duplication may help as a short-term fix, at the expense of a long-term solution. I suppose one could classify duplication in the same category as taking out a large loan at a very high interest rate. You have the money, but it has to be paid back, and that is usually where the problems start. The Template pattern is a pattern that supplies some base functionality, supplemented by a custom class or implementation. It s possible to use the Template pattern in its own context. The problem is that often you don t know what represents common functionality. You can guess common functionality, and probably use base classes for most of it. The problem is that the Template pattern can be applied everywhere, because, after all, isn t object-oriented programming about getting some base class to do some work, and another class to do the rest Yet the Template pattern exists, and must have a purpose. The purpose is to refactor duplicate code that looks similar, but isn t.
EAN / UCC - 14 Generator In VB.NET
Using Barcode printer for VS .NET Control to generate, create EAN 128 image in VS .NET applications.
www.OnBarcode.com
Painting Code128 In Visual Basic .NET
Using Barcode generator for Visual Studio .NET Control to generate, create Code 128 Code Set A image in .NET framework applications.
www.OnBarcode.com
A Duplicate Code Example
Quick Response Code Generation In VB.NET
Using Barcode maker for VS .NET Control to generate, create QR Code ISO/IEC18004 image in VS .NET applications.
www.OnBarcode.com
Barcode Printer In VB.NET
Using Barcode drawer for VS .NET Control to generate, create Barcode image in Visual Studio .NET applications.
www.OnBarcode.com
The following example contains duplicated code. That example will be refactored using the Template pattern. (Note that the data members have been declared as public and not properties to simplify the declaration. Normally properties would be used.)
2D Generation In VB.NET
Using Barcode creator for .NET framework Control to generate, create 2D Barcode image in Visual Studio .NET applications.
www.OnBarcode.com
Uniform Symbology Specification ITF Encoder In VB.NET
Using Barcode printer for .NET framework Control to generate, create ANSI/AIM I-2/5 image in VS .NET applications.
www.OnBarcode.com
CHAPTER 9 REFACTORING TO PATTERNS
Make QR Code In Visual Basic .NET
Using Barcode printer for Visual Studio .NET Control to generate, create QR Code 2d barcode image in VS .NET applications.
www.OnBarcode.com
QR Code 2d Barcode Encoder In Objective-C
Using Barcode generation for iPad Control to generate, create Denso QR Bar Code image in iPad applications.
www.OnBarcode.com
class Item { public int Id; public bool MarkedFlag = false; public Item( int id) { Id = id; } } class DuplicatedInternal { private IList _items = new ArrayList(); public Item GetItem(int id) { foreach(Item item in _items) { if(item.Id == id) { return item; } } return null; } public bool MarkItems() { bool updated = false; foreach(Item item in _items) { if(!item.MarkedFlag) { item.MarkedFlag = true; updated = true; } } return updated; } } This example demonstrates a classical parent-child relationship, where DuplicatedInternal is the parent for Item. The parent contains an array of child elements. This forms the basis of most object hierarchies. When a child element needs to be manipulated, it s necessary to iterate through the individual elements. The methods GetItem and MarkItems perform two different functionalities, but each contains a foreach loop. In the Blob refactoring, the Composite pattern was used to navigate the individual elements. However, even with the Composite pattern, some code has to be repeated in multiple places. The problem with iteration is that it s the same operation of looping through the data. What is different is the code that manipulates the iterated element in the loop. In the methods GetItem and MarkItems, the loops are repeated, but the iterated Item is manipulated in different scenarios. The foreach loop is a very simple example of duplicated code, but it illustrates the architecture of duplicated code.
Decoding Barcode In Visual Basic .NET
Using Barcode decoder for .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Paint Barcode In Java
Using Barcode creator for Android Control to generate, create Barcode image in Android applications.
www.OnBarcode.com
CHAPTER 9 REFACTORING TO PATTERNS
Generating Matrix Barcode In Java
Using Barcode printer for Java Control to generate, create 2D image in Java applications.
www.OnBarcode.com
EAN / UCC - 14 Recognizer In VB.NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Refactoring the Duplicated Code Example
UPC-A Supplement 5 Maker In None
Using Barcode creation for Font Control to generate, create UPC Symbol image in Font applications.
www.OnBarcode.com
EAN13 Scanner In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
Refactoring duplicated code is easy from a theoretical point of view, but requires some thought from a practical perspective. The Template pattern says that a large percentage of the code is delegated to a common type, and the rest is custom implementation.
PDF 417 Recognizer In VB.NET
Using Barcode scanner for Visual Studio .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Scanning Barcode In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
Implementing a Template Pattern Using Inheritance
USS Code 39 Creator In Objective-C
Using Barcode drawer for iPhone Control to generate, create USS Code 39 image in iPhone applications.
www.OnBarcode.com
Encoding PDF 417 In Visual C#.NET
Using Barcode encoder for .NET framework Control to generate, create PDF 417 image in .NET framework applications.
www.OnBarcode.com
Without regard to whether the Template pattern is properly implemented for the context, the following source code is an initial refactoring of the class DuplicatedInternal: class RefactoredIterator< type> { private IList< type> _list; public RefactoredIterator( IList< type> list) { _list = list; } public void Iterate() { foreach( type item in _list) { ProcessItem( item); } } public virtual void ProcessItem( type item) { } } RefactoredIterator<> is a Generic class that contains the common code of the class DuplicatedInternal. The duplicated code is the iteration of a list of elements. So that RefactoredIterator<> remains flexible, the Generic parameter is the type being iterated, and for DuplicatedInternal, that would be the type Item. For each iteration, the method ProcessItem is called, which is defined as a virtual method. The idea is that DuplicatedInternal should subclass RefactoredIterator<> and implement the method ProcessItem. In the implementation of ProcessItem, the code would be the loop contents of GetItem or MarkItems. Stepping back, you might notice a disjoint: refactoring out the common code is easy, but making it do the custom work won t work. This is the crux of the problem of why duplicated code isn t recommended. The original developer either knowingly or unknowingly couldn t abstract the duplicated code to use a common code piece. Don t underestimate the complexity of such an undertaking, because it isn t simple to do elegantly. The refactored class RefactoredIterator<> is one solution, but there are some extra details that may or may not be optimal. To understand what I am trying to point out, consider the following refactored DuplicatedInternal class declaration: class DuplicatedInternal { IList< Item> _list = new List< Item>(); public DuplicatedInternal() { } private class InternalGetItem : RefactoredIterator< Item> { public int Id; public Item FoundItem;
Copyright © OnBarcode.com . All rights reserved.