finally again

Cristiano Duarte wrote:

Hi internals !

I came into a problem when writing an IDL to PHP5 language mapping
specification and an IDL to PHP5 language compiler. I'm using the community
OpenORB IDL-to-Java compiler as a base for writing the IDL-to-PHP5 compiler,
in fact, it is a translation from Java to PHP5. Everything is ok except the
"finally" clause wich doesn't exists in Zend Engine 2. I know that many of
you think that "finally" is useless but consider this case, and if anyone
have a simple and elegant solution without implementing "finally" I'll be
glad to listen.
That's great! An IDL to PHP compiler is really needed !
What's the status of your project anyway ?
I'm not shure, but I guess Marcus said that finally is useless in PHP...

The code would be like this if we had finally:
<?
...
$_input = null;
try {
$_output = $this->_request('bind',true);
org__omg__CosNaming__NameHelper::write($_output,$n);
$_output->write_Object($obj);
$_input = $this->_invoke($_output);
return;
} catch(org__omg__CORBA__portable__RemarshalException $_exception) {
continue;
} catch(org__omg__CORBA__portable__ApplicationException $_exception) {
$_exception_id = $_exception->getId();
if ($_exception_id == org__omg__CosNaming__NamingContextPackage__NotFoundHelper::id()) {
throw org__omg__CosNaming__NamingContextPackage__NotFoundHelper::read($_exception->getInputStream());
}
if ($_exception_id == org__omg__CosNaming__NamingContextPackage__CannotProceedHelper::id()) {
throw org__omg__CosNaming__NamingContextPackage__CannotProceedHelper::read($_exception->getInputStream());
}
if ($_exception_id == org__omg__CosNaming__NamingContextPackage__InvalidNameHelper::id()) {
throw org__omg__CosNaming__NamingContextPackage__InvalidNameHelper::read($_exception->getInputStream());
}
if ($_exception_id == org__omg__CosNaming__NamingContextPackage__AlreadyBoundHelper::id()) {
throw org__omg__CosNaming__NamingContextPackage__AlreadyBoundHelper::read($_exception->getInputStream());
}
throw new org__omg__CORBA__UNKNOWN("Unexpected User Exception:$_exception_id");
} catch(Exception $_exception) {
throw $_exception;
} finally {
$this->_releaseReply($_input);
}
...
?>
Humm...

Since we don't have finally, the current code is:

<?
...
$_input = null;
try {
$_output = $this->_request('bind',true);
org__omg__CosNaming__NameHelper::write($_output,$n);
$_output->write_Object($obj);
$_input = $this->_invoke($_output);
$this->_releaseReply($_input); //PHP still does not have FINALLY !!!
return;
} catch(org__omg__CORBA__portable__RemarshalException $_exception) {
$this->_releaseReply($_input); //PHP still does not have FINALLY !!!
continue;
} catch(org__omg__CORBA__portable__ApplicationException $_exception) {
$_exception_id = $_exception->getId();
if ($_exception_id == org__omg__CosNaming__NamingContextPackage__NotFoundHelper::id()) {
$this->_releaseReply($_input); //PHP still does not have FINALLY !!!
throw org__omg__CosNaming__NamingContextPackage__NotFoundHelper::read($_exception->getInputStream());
}
if ($_exception_id == org__omg__CosNaming__NamingContextPackage__CannotProceedHelper::id()) {
$this->_releaseReply($_input); //PHP still does not have FINALLY !!!
throw org__omg__CosNaming__NamingContextPackage__CannotProceedHelper::read($_exception->getInputStream());
}
if ($_exception_id == org__omg__CosNaming__NamingContextPackage__InvalidNameHelper::id()) {
$this->_releaseReply($_input); //PHP still does not have FINALLY !!!
throw org__omg__CosNaming__NamingContextPackage__InvalidNameHelper::read($_exception->getInputStream());
}
if ($_exception_id == org__omg__CosNaming__NamingContextPackage__AlreadyBoundHelper::id()) {
$this->_releaseReply($_input); //PHP still does not have FINALLY !!!
throw org__omg__CosNaming__NamingContextPackage__AlreadyBoundHelper::read($_exception->getInputStream());
}
$this->_releaseReply($_input); //PHP still does not have FINALLY !!!
throw new org__omg__CORBA__UNKNOWN("Unexpected User Exception:$_exception_id");
} catch(Exception $_exception) {
$this->_releaseReply($_input); //PHP still does not have FINALLY !!!
throw $_exception;
}
$this->_releaseReply($_input); //PHP still does not have FINALLY !!!
...
?>

IMHO, I think that replicating the finally code at the end of every catch
block, before every throw/return statement and at the end of the try/catch
statement justify the need of "finally".
Agreed. You pointed out an example that really needs finally.

If there is another aproach without "finally" and without code redundancy, I really need it.
I can't think of another solution right now. But if I figure out
something I'll let you know.

Best Regards,

Andrew Smith, Dr.

Hi Andi,

I've stated my opinion in the past (search the archives) and I don't think
it'd be feasible (nor critical) to implement this...

Do you agree that if we don't have finally we should have a way to catch all exceptions ?

Let me explain:
If you have a library that can raise a huge number of different exceptions and you don't have finally, you should treat all exceptions at the same try/catch block, and rethrow the exceptions that should propagate.
If you have finally, you can treat just the exceptions you need and leave the others to be treated by the caller.

For example: if you don't have finally, don't have a "catch-all" clause and lock some resouce inside a try block, you need to unlock it:
1) in the try block: before every return statement after the resource allocation
2) write a catch block for all possible exceptions that could be raised and put the code before every return/throw statement (this could be dozens of times)
3) at the end of the try/catch block

If you have finally, you just put the same code inside the finally block. No need to catch every exceptions one-by-one, no need to rethrow exceptions that shouldn't be caught, no need to make code redundancy...

I know it's not critical, but IMHO it's important. I hope I was clear enough... :-)

Cristiano Duarte

Hi Andi,

I've stated my opinion in the past (search the archives) and I don't think
it'd be feasible (nor critical) to implement this...

Do you agree that if we don't have finally we should have a way to catch all exceptions ?

Let me explain:
If you have a library that can raise a huge number of different exceptions and you don't have finally, you should treat all exceptions at the same try/catch block, and rethrow the exceptions that should propagate.
If you have finally, you can treat just the exceptions you need and leave the others to be treated by the caller.

For example: if you don't have finally, don't have a "catch-all" clause and lock some resouce inside a try block, you need to unlock it:
1) in the try block: before every return statement after the resource allocation
2) write a catch block for all possible exceptions that could be raised and put the code before every return/throw statement (this could be dozens of times)
3) at the end of the try/catch block

If you have finally, you just put the same code inside the finally block. No need to catch every exceptions one-by-one, no need to rethrow exceptions that shouldn't be caught, no need to make code redundancy...

I know it's not critical, but IMHO it's important. I hope I was clear enough... :-)

Cristiano Duarte