为什么PHP不能捕获在尝试实例化SoapClient对象时导致的异常？

Question

If you dont have the php_soap.dll extension enabled in the php.ini file, trying to create an instance of SoapClient will cause PHP to break.

If i surround the instatiation with a try-catch block like so,

try{
       $client = new SoapClient ($wsdl, array('cache_wsdl' => WSDL_CACHE_NONE) );   
       $result = $client->{$web_service}($parameters)->{$web_service."Result"};
       return $result;
   }
   catch(Exception $e){
        echo $e->getMessage();
   }

it wont catch the excetion. Instead, it is like die()has been called somewhere in the internal PHP code. Does anyone know why this is the case?

note: im using PHP version 7.2.1

Answer 1

As Arvind already pointed out, Errors and Exceptions are two different things in PHP. try/catch works only with Exceptions, not with errors.

Here a little bit more explanation what you can do:

Error handling is defined more or less globally for an application. The built-in error handling checks the severity of the error and depending on this, logs the error and halts the execution.

You can override this behavior by setting a custom error handler using set_error_handler() (http://php.net/set_error_handler).

Quite a common way is to define an custom error handler which raises an Exception. Then you're able to handle errors and exceptions with try/catch in your code. An example error handler which does exactly this is written here: http://php.net/manual/en/class.errorexception.php.

Copied from there the most interessting part:

function exception_error_handler($severity, $message, $file, $line) {
    if (!(error_reporting() & $severity)) {
        // This error code is not included in error_reporting
        return;
    }
    throw new ErrorException($message, 0, $severity, $file, $line);
}
set_error_handler("exception_error_handler");

If you place this code somewhere near to the start of your application, instead of raising errors ErrorExceptions will be thrown. This should work with the SoapClient errors.