function foo ($variable = $this->bar): why doesnt this work?

[figment]

I am curious why if i am inside a class I cannot pass default variables to functions in the form of $this->value:

class some_class {
    $this->variable = $some_value;

function some_function ($arg = $this->variable)
{
    //more code here
}

}

I get errors when I try that... did I miss something? Or is this just not possable. I have found amuch less elegant workaround, but would like to hav the official answer once and for all. Esp. if there is a way to do it, it would make my code much nicer.... and shorter.
Thanks!

[matt_4013]

Hi there, in a class, you don't need to pass your pre-defined variables to the function, just use them, like this:

class foo {

var $var;

function setvar() {

	$this->var = "bar";

	// Rest of your code here

}

// and the rest of your functions!

}

[Weedpacket]

Originally posted by figment
the official answer once and for all.

The official answer can be found in the manual: The default value must be a constant expression, not (for example) a variable or class member.

Howsabout

function some_function($arg=null)
{  if($arg===null) $arg=$this->variable;
}

[figment]

Thank you for your answer, I have already been doing that, I was hoping that there was another with a bit more flexability. I am writing a Web Blog program and had a table with some default values for certain things, but for flexabiliy, i wanted to have several ways to call the function, such that if the user wanted to specify his/her own value they could... this can be seen in the function 'Blog_Page' Where the default value for iSqlLimit is already defined by the class constructor (as retrieved from a database). However the 'end user' would have the option to pass a value of thier own if desired.
see here is what i have now:

class Blogger {
    function Blogger($sInstall_Location)
    {
        if (is_readable($sInstall_Location."configuration_ini.php")) {
            $aConfiguration = parse_ini_file($sInstall_Location."configuration_ini.php", true);
            require($aConfiguration['LOCATION']['install_path']."shr/dal/dal_init.php");
        }
        $this->oDB = new Database;
        $this->Datastream       = $this->oDB->connect($aConfiguration['DATABASE']['host'], $aConfiguration['DATABASE']['user'], $aConfiguration['DATABASE']['pass']);
        $this->sAboutTable      = $aConfiguration['TABLES']['about'];
        $this->sBlogTable       = $aConfiguration['TABLES']['entries'];
        $this->sResponseTable   = $aConfiguration['TABLES']['comments'];
        $this->sCategoryTable   = $aConfiguration['TABLES']['categories'];
        $this->sUserTable       = $aConfiguration['TABLES']['users'];
        $this->sSetupTable      = $aConfiguration['TABLES']['setup'];
        if ($rSetupInfo = $this->oDB->query("SELECT * FROM ".$this->sSetupTable)) {
            $this->aSetupInfo       = $this->oDB->fetch_array($rSetupInfo);
        }
        return $this->aSetupInfo;
    }
}

class Blogger_Entries extends Blogger {
    function Blog_Page($iStartPage = 0, $iSqlLimit = null, $iCat_id = 0, $iBlog_id = null, $sSearchString = null) {
        $this->iStartPage       = $iStartPage;
        if (is_null($iSqlLimit)) {
            $this->iSqlLimit    = $this->aSetupInfo['show_entries'];
        } else {
            $this->iSqlLimit    = $iSqlLimit;
        }
        $this->iCat_id          = $iCat_id;
        $this->iBlog_id         = $iBlog_id;
        $this->sSearchString    = $sSearchString;
        //more code....  more code....
    }
}

zooming in on the function 'Blog_Page' is would be much more elegant I think to have the ability to define it something like this:

    function Blog_Page ($iStartPage = 0, $iSqlLimit = $this->aSetupInfo['show_entries'], $iCat_id = 0, $iBlog_id = null, $sSearchString = null)

thereby eliminating the need for all the IF statements below...

Ahh well, thank you for the answer.

Cheers!