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Exception style

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Jeff Gray

Exception style

I have just watched James Robertson's Exception screencast on exceptions in Pharo.
I haven't really bothered with it previously as I have only played around and haven't done anything in anger.
My commercial background in Java and C# has been with quite different styles of exception handling.
Java was always cluttered with exception handling and re-throwing all through the code whereas in .net it was very much a 'let it bubble up to the container' approach.

Although James screencast shows the mechanics of exceptions I'm wondering what is a normal exception handling strategy in Pharo?
Obvoiusly tutorial code doesn't want to get bogged down with exceptions when trying to teach a specific aspect in smalltalk/pharo/oo etc but I'm yet to see tutorial example code that handles exceptions.

Stéphane Ducasse

Re: Exception style

Hi jeff

It depends. What I saw in the software developed by Hernan wilkinson to manage conferences (Patagonia) is that hernan defines
a lot of specific exceptions. In Core pharo we are a bit learning and cleaning the menu pop up to indicate error. It should be an error and trapped
by the UI manager.

I guess that experts will react on your questions.
Now I do not know if you know the exceptions chapter
http://www.pharobyexample.org/

Stef

On Nov 1, 2011, at 1:35 AM, Jeff Gray wrote:

> I have just watched James Robertson's Exception screencast on exceptions in
> Pharo.
> I haven't really bothered with it previously as I have only played around
> and haven't done anything in anger.
> My commercial background in Java and C# has been with quite different styles
> of exception handling.
> Java was always cluttered with exception handling and re-throwing all
> through the code whereas in .net it was very much a 'let it bubble up to the
> container' approach.
>
> Although James screencast shows the mechanics of exceptions I'm wondering
> what is a normal exception handling strategy in Pharo?
> Obvoiusly tutorial code doesn't want to get bogged down with exceptions when
> trying to teach a specific aspect in smalltalk/pharo/oo etc but I'm yet to
> see tutorial example code that handles exceptions.
>
>
> --
> View this message in context: http://forum.world.st/Exception-style-tp3962162p3962162.html
> Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
>

Mariano Martinez Peck

Re: Exception style

In reply to this post by Jeff Gray

On Tue, Nov 1, 2011 at 1:35 AM, Jeff Gray <[hidden email]> wrote:

I have just watched James Robertson's Exception screencast on exceptions in
Pharo.
I haven't really bothered with it previously as I have only played around
and haven't done anything in anger.
My commercial background in Java and C# has been with quite different styles
of exception handling.
Java was always cluttered with exception handling and re-throwing all
through the code whereas in .net it was very much a 'let it bubble up to the
container' approach.

Although James screencast shows the mechanics of exceptions I'm wondering
what is a normal exception handling strategy in Pharo?

Imagine that in Pharo they would all be "runtime" exception (non-checked was called in Java? I don't remember)... well, that means that the "throws" is not part of the signature and hence a caller doesn't HAVE to mandatory handle the exception. To handle an exception you can do:

[ Transcript show: 'this is the code that I want to execute and may trhow an aexception' ]
on: ThisParticularError
do: [ self manageThisParticularError ]

You can handle Error if you want something more general. You can send #resume to an exception (if possible), etc, etc ec.
As Stef said, read the chapter and ask if you have further questions: https://gforge.inria.fr/frs/download.php/26600/PBE2-Exceptions-2010-03-02.pdf

Obvoiusly tutorial code doesn't want to get bogged down with exceptions when
trying to teach a specific aspect in smalltalk/pharo/oo etc but I'm yet to
see tutorial example code that handles exceptions.

--
View this message in context: http://forum.world.st/Exception-style-tp3962162p3962162.html
Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.

--
Mariano
http://marianopeck.wordpress.com