PHP Fatal error: Can't use method return value in write context

I receive an error message if I uncomment the commented line below. What am I doing wrong?

<?php
class tClass{
	private $var1;
	private $var2;
	
	public function __construct($v1, $v2){
		$this->setVars($v1, $v2);
	}
	
	public function setVars($v1, $v2){
		$this->var1 = $v1;
		$this->var2 = $v2;
	}
	
	public function getVars($var){
		return $this->$var;
	}
}

$eMsg = '';
$inTClass = new tClass('a', 'b');

function testError($postArray = array()){
	foreach($postArray as $post){
		//$inTClass->$setVars($post) = trim($_POST[$post]);
		// uncomment above and get error -  PHP Fatal error:  Can't use method return value in write context
		$tempArray[$post] = trim($_POST[$post]);
	}
	echo "<pre>\n";
	print_r($tempArray);
	echo "</pre>\n";
}

if(isset($_POST['submit'])){
	$varArray = array("var1", "var2");
	$eMsg .= testError($varArray);
}
?>
<form method='POST' name='frmOne'>
	<p>
	</p>
	<span class="fieldlabel">Test Form: </span>
	<input type="text" name="var1" value="<?php echo $inTClass->getVars('var1'); ?>" />
    <input type="text" name="var2" value="<?php echo $inTClass->getVars('var2'); ?>" />
	<p>
        <input class='buttons' type='submit' name='submit' value='Save' />
        <input class='buttons' type='reset' value='Reset' />
    </p>
</form>

PHP:

 

$post is read-only.

 

Shouldn't this:
$inTClass->$setVars($post)

Be:
$inTClass->setVars($post)

Also, the setVars method requires 2 arguments and you're only passing it 1. Lastly, you're trying to call a method and assign a value to it (setVars($post) = trim($_POST[$post])), which makes no sense at all. What you're trying to accomplish here?

 

The code was stripped out of something else, and I rewrote it be much more compact (removing most of the unnecessary stuff). Thought I did a good job till I read your comments. The $setVars issue with regard to $, just didn't see that till you pointed it out. Same goes for the passing in one param where two are required. Thanks.