PHP - Static Class Question

I have 2 php files. I am unable to get B's global variable from A's static method:

A.php
Code: [Select]
class c_A
  { public static function f_A()
      { include_once( "B.php" ) ;
        print f_B() ;
      }
  }
c_A::f_A( ); // only prints "B : "

B.php
Code: [Select]
$gvs = "global variable from B" ;

function f_B()
  { return "B : " . $GLOBALS[ "gvs" ] ;
  }


any thoughts?


thanks,
Shannon

Was just wondering why some people choose NOT to make use of static functions when initializing objects via Factory Classes/Containers.

What are the benefits of initializing the Factory class when for all intensive purposes, it's only used to initialize new classes, etc? 
Does this have any impact on Dependency Injection?  I'm assuming that it doesn't since that would defeat the purpose.

---------

Also, I've noticed that there seems to be an intense stigma within the development community in regard to singletons. 
Are singletons necessarily a bad thing? 

What about database objects? 

One argument I've heard is that this can often impact the flexibility of your application in the event that a new instance of said class needs to be initialized(a second completely separate connection).

However, I was thinking that you could simply store these objects within a static member variable in the factory class; leaving the Database Class' __construct public in the event that you need to create that second/third/fourth connection.

Wouldn't this resolve the issue? 

Hi guys, I am trying something fairly simple but I'm not sure if this would be a good practice. Basically I am using a big class called CommonLibrary that holds common functions as methods and common variables as static variables. But I have some variables here and there like $allAlphabet = range ('a' , 'z'), that cannot be declared as a property because it gives me a parse error.

I don't want to call an object for this class because instancing it is of no use. Values will never change with regards to instances. So the next best thing that I tried was declaring all static variables first, and then changing thei property values inside the class __construct with self::$variable = 'somevalue', and then using this code below to assign values to the empty static variables.


$dummyObject = new CommonLibrary;
unset($dummyObject);
echo CommonLibrary::$staticVariable; // This property is NULL before the constructer is triggered.


Anyone recommend any better ways of doing this?

Thanks in advance!

I thought I was a beginner PHPer but now I'm not even sure I'm that. I have this class here which starts with:
Code: [Select]
    private static $FormatType = "";
but then further down:
Code: [Select]
    public function SetFormatType($NewFormatTypeId)
    {
        $this->FormatType = $NewFormatTypeId;
    }
    public function GetFormatType()
    {
        return $this->FormatType;
    }
Do you suppose that the original developer just had a singleton or something, then latter on he found that he was making more instances and PHP tolerates this behavior? Or am I missing something?

I'm starting to use a class to perform DB functions because I think it is more efficient. I found this class on the internet and understand pretty well what is going on. My problem is that I can't put the results on the screen when I use the class. (I can do it with out using the class but I'd like to learn to use it)

function fetch($info) {
        return mysql_fetch_array($info);

this is how I'm attempting to use it

$db = new mysql;
$db->connect();

while($row = $db->fetch($db->query("SELECT * FROM Attributes")))
{
echo $row['Attribute']."<br>";
}
This just echos the first row forever and I'm not sure how else to go about this. Any help would be appreciated.

Why is the proper way to call a class is to call a method at the same time?

For example
Code: [Select]
$class = new SomeClass();
$class->some_method();

I understand why you would do this but lets say you just have a simple class that you pass some data.  The class than processes the data in some way than returns it.  It is my understanding if you were to make a class likes this.

Code: [Select]
class SomeClass{

     function __construct($data){
          //process data//
          return $data;
    }
}

That this code is considered an improper way of doing this because you should never return data from the __construct.  So would this follow code be the proper way to handle this?

Code: [Select]
class SomeClass{

     function __construct($data){
          $this->some_method($data);
    }

     function some_method($data){
          //process data//
          return $data;
    }
}

Any good explanation on the proper way to handle this would be greatly appreciated.  When I am making simple classes to do a specific task it would seem more efficient not having to know about any particular method inside the class. 

Hello,

I'm doing something that looks like framework. It's my first serious "project". And now, I have a few questions: what basic functions are needed in MVC model class? Just tell me some functions, that could use, so I could try to code them. And the next question is... I'm going to create a login system for users. In my website there will be pages, that are visible for all visitors, and only for members. For example main website page should be visible for all visitors, but the page, where member can change his password, should be visible only for member. I know only one way to do this: allways and everywhere check if user is logged in. But isn't there smarter and simpler way?

I hope you understood what I need. Sorry for bad english

Hi,

I'm newbie to php opp.

I just need to know if it is possible to instantiate a class like this?



$import = new geoIpImportCSV(obtainDownloadFileName(), 'table1');

class geoIpImportCSV {

private $input_zip_file;
private $db_table;  

function __construct($input_zip_file, $db_table) {
$this->input_zip_file = $input_zip_file;
$this->db_table       = $db_table;
}

/*
"GeoLiteCity_" . $date . ".zip".
*/
function obtainDownloadFileName() {
return "GeoLiteCity_20101201.zip";
}

    // ...
}


It is possible to call a method(obtainDownloadFileName()) like this to the constructor?

Best Regards,

OK so sorry if my understandings a bit off, but if a I want to introduce a class into my doc is the best way to fo this with the include() function?

I created a database class to connect to a database.  The code is below.  I'm not sure how to call this connection in other classes.  Do I use:

$db->pdo = $conn->prepare($sql);

or what?  Note that the db object is instantiated at the end of the class file.  Here is the class:

 

class DB {
	
	public $pdo = '';
	//public $message = 'A message from db'; // Debug

function __construct() {
	
	// Database info located elsewhere
	$servername = "localhost";
	$username = "root";
	$password = "";
	$dbname = "dbname";
	
	try {
		
	  $this->pdo = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
	  // set the PDO error mode to exception
	  $this->pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

	}  // End Try
	
	catch(PDOException $e) {
		  echo "Error: " . $e->getMessage();
		}
		
		//echo '<h3>Everything wnet OK.</h3>';  // Debug

	} // End __construct
	
} // End class definition DB.php

$db = new DB;

Thanks,

 

--Kenoli

I'm confused as to why assigning these variables in the class causes the page not to load...


var $RootFolder = '/shyid/';
var $PagePath = str_replace($this->RootFolder, '', dirname($_SERVER['PHP_SELF']));
var $PageSections = explode('/', $this->PagePath);


but when i set them on the page, everything works correctly?


$head->RootFolder = '/shyid/';
$head->PagePath = str_replace($head->RootFolder, '', dirname($_SERVER['PHP_SELF']));
$head->PageSections = explode('/', $head->PagePath);


Insight? Thanks.

Imagine 6 PHP classes (one each for a product line), that have very similar coding structures, that go like this:

//function that computes stuff inside each of 6 files:
//they vary slightly from file to file but essentially it is this:
function computeFunction
{
    $this->x = new X();

    $this->x->calcD();

    if ($this->x->dOk)
    {
        $this->x->calcE();
        $this->x->calcN();   
    }

    //more complicated logic that is essentially like above

    //and by the way!
    print $this->x->someVarThatIsUsedLater;
}

Then there is a single class like so :

class X
{
    function calcD()
    {
        //compute some condition

        if (<computed condition is met>) $this->dOk = true;
        else $this->dOk = false;

        //and by the way
        $this->someVarThatIsUsedLater = 4;
    }
}

Just to bring your attention to it, none of these functions return any result or value, but they nevertheless operate on variables of key interest via side-effects.  That is, they modify variables that essentially act like globals, and then use those variables later ($this->dOk and $this->someVarThatIsUsedLater are one more prominent examples).   I need to untangle this mess.  And make it clean and clear again, and make sense.  How do I best proceed?   I have been wrestling with some ideas... like $this->dOk, can within reason be turned into a return variable of calcD() function, and then be tested against like if ($this->x->calcD()) and I think it will be reasonable enough.  But then there are other functions that don't return anything and just act on variables via side-effects anyway so $this->dOk is one of the lesser troubles...   Other than that, what I am thinking of doing is getting rid of these mini-functions (calcE(),  calcN(), etc.), removing them as a funciton, and putting their body directly into the code, as a first step to refactor.  Many of the computations done inside are just a few lines of code anyway, and the functions kind of hide a lot of side-effects that happen, instead of actually encapsulating the behavior.  So while it may be counter-intuitive to dismantle the functions that appear to be doing something that normally can be encapsulated (computing key variables E, N, etc), I think dismantling them will actually clean things up as far as collecting all the side-effects inside a single parent function thereby making them more visible.   Caveat:  while doing so I will end up with 6 copies of untangled dismantled functions, because dismantling class X and putting its content into each of the 6 product line classes will have that effect.   But my hope is that from that point I will see more clearly to start identifying places where I can start to truly encapsulating the behavior via various structures, instead of masking it.   Problems / Questions: I would like to but I am not entirely sure that I can skip that step of dismantling functions & the 6x multiplying effect. It's probably the same like skipping steps in solving polynomial equations.  Some can do it and some need to list each step of their work. And I am not entirely sure what structures I can replace it with in the end after I dismantle the functions. It also looks like a lot of work.  Is there a better way? P.S. I already put tests on computeFunction() for each product line so I can be less paranoid about hacking stuff up.
Edited by dennis-fedco, 19 January 2015 - 03:06 PM.

I have mysqli object in Database class base:

[color=]database class:[/color]

class Database {
  private $dbLink = null;
  
  public function __construct() {
    if (is_null($this->dbLink)) {
      // load db information  to connect
      $init_array = parse_ini_file("../init.ini.inc", true);
      $this->dbLink = new mysqli($init_array['database']['host'],
                           $init_array['database']['usr'],
                           $init_array['database']['pwd'],
                           $init_array['database']['db']);
  
      if (mysqli_connect_errno()) {
        $this->dbLink = null;
      }
    }
  }

  public function __destruct() {
    $this->dbLink->close();
  }
}


Class derived is Articles where I use object dBLink in base (or parent) class and I can't access to mysqli methods (dbLink member of base class):

Articles class:

require_once ('./includes/db.inc');

class Articles extends Database{
  private $id,
              ....
              ....
             $visible = null;
  
  public function __construct() {
    // Set date as 2009-07-08 07:35:00
    $this->lastUpdDate = date('Y-m-d H:i:s');
    $this->creationDate = date('Y-m-d H:i:s');
  }
  
  // Setter
  ....
  ....

  // Getter
  ....
  ....

  public function getArticlesByPosition($numArticles) {
    if ($result = $this->dbLink->query('SELECT * FROM articles ORDER BY position LIMIT '.$numArticles)) {
      $i = 0;
      while ($ret = $result->fetch_array(MYSQLI_ASSOC)) {
        $arts[$i] = $ret;
      }
      $result->close();
      return $arts;
    }
  }
}


In my front page php I use article class:


include_once('./includes/articles.inc');
$articlesObj = new articles();
$articles = $articlesObj->getArticlesByPosition(1);
var_dump($articles);


[color=]Error that go out is follow[/color]

Notice: Undefined property: Articles::$dbLink in articles.inc  on line 89

Fatal error: Call to a member function query() on a non-object in articles.inc on line 89

If I remove constructor on derived class Articles result don't change 
Please help me

I have an existing instance of my class Database, now I want to call that instance in my Session class, how would I go about doing this?

Ok. I know you can pass the object of a class as an argument. Example:


class A {
    function test() {
        echo "This is TEST from class A";
    }
}


class B {
    function __construct( $obj ) {
        $this->a = $obj;
    }

    function test() {
       $this->a->test();
    }

}


Then you could do:

$a = new A();
$b = new B($a);


Ok so that's one way i know of.

I also thought that you could make a method static, and do this: (assuming class A's test is 'static')

class B {
    function test() {
       A::test(); 
   }
}


But that is not working.


I'd like to know all possible ways of accomplishing this. Any hints are appreciated. thanks