Exceptions

[knowj]

I have recently been looking into exceptions and setting up a more comprehansive error catching/reporting system that will notify me of any errors that happen within my systems.

The literature i have been reading always involves using try on every bit of code which is written then throwing an exception if an error occurs which is then caught by another statement performing the error reporting functionality.

If there a way without having to do something along these lines:

class FileReader{
  private $file;
  private $fileDir='fileDir/';
  public function __construct($file){
    if(!file_exists("{$this->fileDir}{$file}.php")){
      throw new FileException('File '.$file.' not found');
    }
    $this->file=$file;
  }
  public function getContent(){
    if(!$content=file_get_contents("{$this->fileDir}{$this-
file}.php")){
      throw new FileException('Unable to read file contents');
    }
    return $content;
  }
  public function mailContent(){
    if(!mail('Recipient<[e-mail]>','HTML Page',$this-
getContent())){
      throw new MailException('Unable to send by email file
contents');
    }
  }
}

try{
  $fr=new FileReader('sample_file');
  // email file content
  $fr->mailContent(); // potential error condition
  // echo file content
  echo $fr->getContent(); // potential error condition
}
// catch FileException
catch(FileException $e){
  $e->showError();
}
// catch MailException
catch(MailException $e){
  $e->logError();
}

I was thinking something more along the lines of throwing exceptions on each error occurance then catching/performing the reporting within the destruct of each class.

I don't know how viable this is. also does anyone have any decent references/uses of exceptions within a system.

thanks in advance.

[laserlight]

I was thinking something more along the lines of throwing exceptions on each error occurance then catching/performing the reporting within the destruct of each class.

I am not sure what you mean by that, some elaboration would help.

[knowj]

I was thinking of something along the lines of throwing exceptions within my methods (for instance within the database connection method - database class constructor) if an error occurs then within the destruct of the database class catch the exception and email/log the error.

Does that help explain atall?

Cheers
j

[Weedpacket]

knowj wrote:

The literature i have been reading always involves using try on every bit of code which is written then throwing an exception if an error occurs which is then caught by another statement performing the error reporting functionality.

Yuck; what literature is this? Exceptions are expensive and should only be used in exceptional circumstances.

Like this example:

  public function mailContent(){
    if(!mail('Recipient<[e-mail]>','HTML Page',$this-
getContent())){
      throw new MailException('Unable to send by email file
contents');
    }
  } 

What's wrong with just returning a true or false, and having the caller decide what should be done with the result (like, handle it, or throw its own exception if it can't figure out what to do)?

[knowj]

Well that is essentially what i want to do. I want to have a low level error reporting system in place that will return when any key functionality of the system performs an error:
+ database connection
+ adding a product to a store etc...

Allowing the exceptions to handle the error reporing that I won't want to have to rewrite for each system i implement.

Obvisouly have simple top level reporting for the user without exceptions (possibly) but have the exceptions handle the more integeral workings of the system.

My main problem is the lack of documentation on how to handle exceptions within an web application.

[NogDog]

There's always the [man]set_exception_handler/man function, if what you want is a default means of handling uncaught exceptions. On the other hand, if your main concern is simply logging debug data, you can use [man]set_error_handler/man, have it do whatever error logging/handling you want, and then trigger it via [man]user_error/man as needed in your methods (and then can still simply return false on failure where an exception is overkill).