Adapter pattern using php

Programming would be simple, but boring. Programmers would continue to build applications on top of the same technologies that they did years ago. They would never need to introduce different databases, implement new best practices, or consume different APIs. But these things do change. Luckily, programmers have the Adapter Design Pattern to help update legacy systems with new code and functionality.

The solution is to build another object, using the Adapter Design Pattern. This Adapter object works as an intermediary between the original application and the new functionality. The Adapter Design Pattern defines a new interface for an existing object to match what the new object requires.

Code Example

In the original code base of the project, an object exists that handles all of the error messages and codes called errorObject. The original programmers didn’t think their code would ever generate any errors, so they designed the system to output the errorObject’s error information directly to the console.

In this example, a 404:Not Found error is being generated. You are going to assume that the error message content and code may change, but the text will always stay in the same format.

 class ErrorObject  
 {  
   private $error;  
   public function __construct($error){  
     $this->error = $error;  
   }  
   public function getError(){  
     return $this->error;  
   }  
 }  

 class LogToConsole  
 {  
   private $errorObject;  
   public function __construct($errorObject){  
     $this->errorObject = $errorObject;  
   }  
   public function write() {  
     fwrite(STDERR, $this->errorObject->getError() . "\n");  
   }  
 }  

Here is the testing...

 include "ErrorObject.php";  
 include "LogToConsole.php";  
 /** create the new 404 error object **/  
 $error = new ErrorObject("404:Not Found");  
 /** write the error to the console **/  
 $log = new LogToConsole($error);  
 $log->write();  

How about new requirement comes that error need to output to csv format, with the code and description.

Lets look at how we going to do that with Adapter pattern.

 class LogToCsvAdapter extends ErrorObject  
 {  
   private $errorNumber, $errorText;  
   public function __construct($error)  
   {  
     parent::__construct($error);  
     $parts = explode(':', $this->getError());  
     $this->errorNumber = $parts[0];  
     $this->errorText = $parts[1];  
   }  
   public function getErrorNumber()  
   {  
     return $this->errorNumber;  
   }  
   public function getErrorText()  
   {  
     return $this->errorText;  
   }  
 }  

Here is the testing...

 include "ErrorObject.php";  
 include "LogToCsv.php";  
 include "LogToCsvAdapter.php";  
 /** create the new 404 error object adapted for csv **/  
 $error = new LogToCsvAdapter("404:Not Found");  
 /** write the error to the csv file **/  
 $log = new logToCSV($error);  
 $log->write();  

Good luck...

How to delete .svn files for linux

Recursively delete .svn directories

This is a simple example of a unix command, which recursively deletes subversion .svn folders. Subversion is a well-spread open-source revision control application. Every copy of source code received from subversion repository has .svn folders, which store metadata. However, if you want to use or distribute source code, these .svn folder are often not necessary.     

We use find command to find all .svn folders beginning from current directory.

eg: type : find . -type d -name .svn

It is possible to pass these directories directly to rm command, using grave accent quotes (key to left of '1')

eg: type : rm -rf `find . -type d -name .svn`

above command will remove every .svn folder beginning from current directory.

You may do not like to type each and every time so you can create shell script for that.

1) Create a file called  /usr/bin/csvn 

2) Input following codes:

#!/bin/sh
echo "recursively removing .svn folders from"
pwd
rm -rf `find . -type d -name .svn`

You may save this script to /usr/bin/csvn (or other binary folder included in path) and use later to get 'clean' project source without typing lengthy commands.

For example

$ svn checkout svn://server.com/svn/project
A    project/index.php
A    project/sourceA/a.php
A    project/sourceA/a1.php
A    project/sourceA/a2.php
A    project/sourceB/b.php
A    project/sourceB/module/lib.php
A    project/sourceC/c.php
Checked out revision 15.
$ cd project
$ csvn
recursively removing .svn folders from
/Users/anyexample/Source/project

~Good luck~