PHP/FI had a quirky function declaration syntax:

function sum $a, $b (
    return($a + $b);
);

This was changed in PHP 3, but you could continue to use the old form in PHP 3 and PHP 4 if you declared your function as an old_function:

old_function sum $a, $b (
    return($a + $b);
);

Alas, after six years, this backward compatibility feature is now gone. Another nostalgic remnant of PHP/FI has passed away.

I must say, I used PHP/FI, but I never resorted to the old_function hack to ease my PHP 3 migration issues.

Did anybody ever use this?

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Therefore, I’ll pull out a few lines, combine that with some hand waving, and just hope for the best. Here’s the before:

$wsdl = 'http://developer.ebay.com/webservices/latest/eBaySvc.wsdl';
$client = new SoapClient($wsdl);

$params = array('Query' => 'ipod');
$results = $client->GetSearchResults($params);

foreach ($results->SearchResultItemArray->SearchResultItem as $item) {
  print $item->Item->Title . "\n";
}

Without the classmap option, I create a SoapClient, make my request, and then iterate through the results to print out the titles of the matching items. This isn’t complex; however, the iteration is a little klunky due to limitations of SOAP and the design of eBay’s Web service.

For example, the SearchResultItemArray only contains SearchResultItem, so it’s kludgy to reference SearchResultItemArray->SearchResultItem. Likewise, when I’m just getting a quick dump of Item information, it’s not so nice to specifically access the Title element.

By defining a couple of classes and telling the SoapClient object map them to the return data, I can clean this up:

class eBaySearchResultItemArrayType implements IteratorAggregate {
  public function getIterator( ) {
    return new ArrayObject($this->SearchResultItem);
  }
}

class eBaySearchResultItemType {
  public function __toString() {
    return $this->Item->Title . "\n";
  }
}

$wsdl = 'http://developer.ebay.com/webservices/latest/eBaySvc.wsdl';
$options = array('classmap' => array(
  'SearchResultItemArrayType' => 'eBaySearchResultItemArrayType',
  'SearchResultItemType' => 'eBaySearchResultItemType',
  ),
);

$client = new SoapClient($wsdl, $options);

$params = array('Query' => 'ipod');
$results = $client->GetSearchResults($params);

foreach ($results->SearchResultItemArray as $item) {
  print $item;
}

To solve my first problem, the iteration, I make eBaySearchResultItemArrayType implement the IteratorAggregate interface. When a PHP 5 class implements this interface, PHP will invoke the getIterator() method during a foreach loop.

In this case, I return $this->SearchResultItem, wrapping it inside an ArrayObject to make the array iterable.

For the pretty-printing issue, I define a __toString() method inside of eBaySearchResultItemType. Now, when I print an instance of this class, PHP calls that method instead.

With my classes defined, I use the classmap option to map the PHP classes to the SOAP complexTypes, and pass this mapping along as part of the second parameter to the SoapClient constructor.

Once this is set up, everything else in the request is identical. However, when I print out the results, the syntax is clean:

foreach ($results->SearchResultItemArray as $item) {
  print $item;
}

At one level, this is just syntax and icing. However, I don’t think you should dismiss syntax with a wave of your hand. To quote Sam Ruby on C# and LINQ:

[S]yntax matters. Very much so.

So, I am convinced that this is a good thing to spend time on. There are a couple other tricks I’ve pulled out, such as:

class eBayFeesType implements ArrayAccess {

  public function offsetGet($offset) {
    foreach ($this->Fee as $value) {
      if ($value->Name == $offset) {
        return $value;
      }
    }
  }

  /* and the other interface methods... */
}

class eBayFeeType {
  public function __toString() {
    return (string) $this->Fee->_;
  }
}

This lets me do:

echo "Listing fee is: ", $results->Fees['ListingFee'], "\n";

Which I must say is far nicer than either iterating in place or even calling out to a utility method.

I was interested to discover that I needed to manually cast $this->Fee->_ to a string because I thought it was a string. Actually, it is a float, and PHP won’t autocast floats to strings in this instance.

Personally, I think if PHP should autocast here, but I can see the logic. If you’re promising to return a string, you should actually return one.

At first, I was writing each class by hand. But that got boring and wasn’t scalable. Therefore, my new goal is to automate this process. I am writing a script to read the WSDL file, parse out the complexTypes, and then convert them to PHP classes.

My original script was using the SoapClient::__getTypes() method as a pre-processor, but I needed to parse that output again to get it into a usable format. After a little digging, I discovered that PEAR::SOAP implements its own parsing routines and gives me a far more flexible PHP data structure to manipulate. So, I am going in that direction instead.

Since this is a one-time action, speed isn’t vital, so it’s okay that PEAR::SOAP is written in PHP.

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