Loading templates from a class break the code

[webdevindex]

I just coded a class for loading template/pages; simplified:

class tpl {
    function getTpl($file) {
        include 'templates/'.$file;
    }
}

$tpl = new tpl();
$mysql = new mysql();
$tpl->getTpl("mytemplate.php"); 

A template may include code like this:

<?=$mysql->getData();?>

Now i get "Fatal error: Call to a member function getData() on a non-object".
From what i understand the included file works from within the tpl class and therefore it can't access the mysql class.

What alternatives do i have, any suggestions on how to solve this?
The solutions i have soo far:
* Skip the tpl class and just use include 'template';
* Send some kind of reference of mysql class to tpl class, new tpl(new mysql), but since i have around 20 classes that may or may not be used inside the template i don't like this one.

Thanks

[webdevindex]

I have tried experimenting with ob_start/ob_get_clean and the Factory pattern/method but i don't see how i could get it to work.

[kyberfabrikken]

$mysql is a variable, not a class. A class is a code-structure, like a function.
Your template-code can't access the variable, because it's in a different scope. See variables.scope and php variable scope for an explanation.

[Ren]

$mysql is out of scope when your template is called
One alternative is..

class tpl { 
    private $vars;

function set($name, $var) { $this->vars[$name] = $var; }

   function getTpl($file) { 
        extract($this->vars);
        include 'templates/'.$file; 
    } 
} 

$tpl = new tpl(); 
$tpl->set('mysql', new mysql());
$tpl->getTpl("mytemplate.php"); 

[webdevindex]

$mysql is a variable, not a class. A class is a code-structure, like a function.

Well actually its and object right?

Your template-code can't access the variable, because it's in a different scope.

Yes thats what i have figured out, what i haven't figured out is a good solution to this

[webdevindex]

Thanks ren, thats worth looking into

[kyberfabrikken]

Well actually its and object right?

Yes, an object is a specific type of variable.

Yes thats what i have figured out, what i haven't figured out is a good solution to this

It's a very basic problem. I assume you're new to programming in general, or to OOP in particular ?
When calling a function, the variable-scope changes. Normally, only variables which are declared within the current scope are accessible. If we only focus on procedural programming (no objects/classes), the scope changes when you call a function - The function has it's own scope. You have two ways of passing a variable from the calling scope and into that functions scope. Either you pass it as an argument to the function, or you declare it global. The latter is bad practice and should be avoided.
The following should illustrate :

function test() {
    echo $foo; // an undefined local variable
}
function test2() {
    $foo = 53; // a local variable
    echo $foo;
}
function test3($foo) { // the variable gets passed in as a parameter
    echo $foo;
}
function test4() {
    global $foo; // the variable gets passed in as a global variable
    echo $foo;
}
function test5() {
    global $foo;
    $foo = 53;
    echo $foo;
}
$foo = 42;
echo $foo; // will output 42
test(); // will not output anything
$test2(); // will output 53
echo $foo; // will still output 42
$test3($foo); // will output 42
$test4(); // will output 42
$test5(); // will output 53
echo $foo; // will now output 53 

With objects, you get another option for passing variables. Since methods (functions) belongs to an object, you can assign variables to that object and use it as a "marketplace" so to speak. Consider this :

class MyClass
{
    var $foo;
    function test() {
        echo $this->foo;
    }
}
$myObject = new MyClass();
$myObject->foo = 42;
$myObject->test(); // will output 42 

[webdevindex]

No not really but i didn't know that when using a class to include a file the included file becomes part of that class-scoop. This would make it practually impossible to use a class for loading files since the code inside that file can't access anything else. :P

[bubblenut]

...or, if you look at it another way. It's a brilliant way of restricting what is available to particular template, take the following for example.

class Template($file) {
  private $file;

  public function __construct($file) {
    $this->file = 'templates/'.$file;
    if(!file_exists($this->file)) {
      throw new InvalidArgumentException("File not found");
    }
  }

  public function render() {
    include $this->file;
  }
}

$somethingsecret = "Don't tell anyone about this, it's a secret";
$template = new Template('test.php');
$template->myvar = 'some data';
$template->render();

{{{test.php}}}
<?php
if(isset($somethingsecret)) {
  echo("$somethingsecret\n");
} else {
  echo("No secrets here, move along please\n");
}

if(isset($this->myvar)) {
  echo("You're allowed to see {$this->myvar}\n");
} else {
  echo("Nothing to see here, move along please\n");
}

Now, the template can only access variable you specifically say it can. You should see

No secrets here, move along please
You're allowed to see some data

[stereofrog]

class tpl {
    function getTpl($file) {
        include 'templates/'.$file;
    }
}

$tpl = new tpl();
$mysql = new mysql();
$tpl->getTpl("mytemplate.php"); 

Why not

class tpl {
    function getTpl($file) {
        return 'templates/'.$file;
    }
}

$tpl = new tpl();
$mysql = new mysql();
include $tpl->getTpl("mytemplate.php"); 

[Captain Proton]

...or, if you look at it another way. It's a brilliant way of restricting what is available to particular template, take the following for example.

global $somethingsecret .. ?

[bubblenut]

Oh yea
Must remember to think before I speak

[webdevindex]

Thanks for all replys, can't decide if i´ll go with stereofrog or ren's suggestion.
Whats best? To pass the objects to the included file (ren) or to include the file in the "global scope".

Yes i understand that this probably depends on what you want to do, but is anyone of these considered bad practice?

Thanks again for your patience :I)

[Dr Livingston]

> Whats best?

Rens example of use would proberly give you greater scope...

[Galo]

I have tried experimenting with ob_start/ob_get_clean and the Factory pattern/method but i don't see how i could get it to work.

That's why we have interfaces and loose typing, cool combo

anyway,

ob_start();

$myNewTemplateContent = ob_get_contents();

ob_flush_end();

return($myNewTemplateContent);

should do the trick, andaahh, <?=$mysql->getData();?> ?!?!?!? looks more like a static member to me in myAppp_mySqlDataManager::getData($templateID); or something like it....

[webdevindex]

Ok now i have tried this for a while. Right now i load all my templates inside the tpl class and in the templates i use $this->function(); so i never use functions outside the tpl scoop in the templates. But the tpl class itself might call other classes / functions.

Example

class tpl {
    function doSomething($str)
    {
          return do::Something($str);
    }
    function getTpl($file) {
        include 'templates/'.$file;
    }
} 

So if i want to call a class or function from inside my templates i'll add that to the tpl class. Is this bad in any way? In this case i could just use do::Something($str) inside the tempate. Don't know why i did this, maybe to have controll over whats called/running inside the template.