Error passing DOMDocument through functions - php

Question

Im writing a web crawler in PHP and I wrote a re-usable xPath evaluator.The function is:
function xPathEvalSingle($soruce, $xpathExpression) {
$resultsFromXpath = $source->evaluate($xPathExpression)->item(0)->textContent;
return $resultsFromXpath;
}
I create a new DOMXPath object and load from a valid HTML page:
$page = $this->getPageHtml($newCrawlUrl);
$source = new DOMXPath($page);
Then call the function:
xPathEvalSingle($soruce, $xpathExpression) = Fatal error: Call to a member function evaluate() on a non-object
However, when I do it without a function, I get what I want
$resultsFromXpath = $source->evaluate($xPathExpression)->item(0)->textContent = What I want
How would I properly pass the DOMXPath to the function to make it work?

Answer 1

Increase you error reporting level to include notices. You have the same variable typo $soruce in the declaration and the call of the function.
That means in the call an undefined variable is used.
Example:
<?php
error_reporting(E_ALL);
$source = 42;
print($soruce);
Output:
Notice: Undefined variable: soruce in /tmp/... on line 4
Inside the function the argument is not used, but an unknown variable $source.
Example:
<?php
error_reporting(E_ALL);
function foo($soruce) {
print($source);
}
foo(42);
Output:
Notice: Undefined variable: source in /tmp/... on line 5