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Re: [udig-devel] standard way to do file access and exception throwing
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Addison Wesley has a good eclipse book series. In particular:
Contributing to Eclipse
SWT: The standard widget tookit
Eclipse RCP.
Jesse
On 15-Feb-07, at 12:55 AM, Andrea Antonello wrote:
1) what is used to wrap a file access in a standard way? We had
something like a datasource which just decided if it was a file:
or smb:
or http: and had facilities to get readers, writers, stream and
so. I'm
sure this is also in udig, but I can't find it. If not, what is the
logic to follow?
I don't have a good answer here. Jody?
I have looked at catalog implementations that take this approach;
uDig
does not provide this kind of low level support. It is more a
platform
for visually integrating what you already have. Thinking ...
Alright, it was just that I didn't feel good to use File and
BufferedReader or RandomAccessFile without thinking about remote
files.
However a JGrass database will always be local, so I don't think there
will be problems. But you never know :)
If you look at recent eclipse builds they have done a neat trick.
They
have methods on their IResource instances that return something
that is
"almost" like a Java File. Pretty sure this is in Eclipse 3.2?
Can you look at this facility and see if it works for you? I would
like
to stick with normal eclipse constructs as often as possible.
I would be delighted, but I need a clearer direction to look at.
I'm an
eclipse framework newbie...
2) how to properly throw exceptions? When to send in red to the
statusbar? Is there a way to open a dialog with the error
description
and a log to send? How is this dealth with in general?
We follow eclipse conventions; usually each extension point lets you
know what you are allowed to do. My preference is to have the
extension
point processor take care of error reporting, setting a warning in
the
status bar (or simply attaching a warning to a GeoResource etc...).
Can I ask for the specific context in which you are trying to
handle the
Exception? For a uDig operation you should just be able to
"throw" and
uDig will take care of the notification.
Great. That is perfect.
For Tool things are a bit more
scary (since an error may be in the event loop).
We haven't nicely come up with a solution to this yet. The main
thing
we do is add a logging method in the Activator class of the
plugin and
directly log to that. There are a few areas that you can put
errors.
One place is on the GeoResource or Service. There is an error
message
and a Throwable that you can set. If you are in a renderer you just
have to throw an exception and it will be set in the status bar for
that layer. Layers also have a status and a status message. This
is an issue that needs to be better discussed at some point as it is
kind of ad hoc now. I think Cory started an ErrorManager but it
is a
long way from complete.
Hi Jesse :-) You are on the same page as me. Andrea we can check our
eclipse books again to see if there is any best practice we have
missed
out on. But so far normal Framework advice is the best (capture the
error handling as part of managing the extension point and don't
force
any error handling code on contributors).
Yes, that is very nice, if you are a contibutor like me :)
You were talking about eclipse books. Could you give me some reference
to a good book that also covers SWT? I think copy and paste won't be
enough at a certain point. :)
Andrea
_______________________________________________
User-friendly Desktop Internet GIS (uDig)
http://udig.refractions.net
http://lists.refractions.net/mailman/listinfo/udig-devel
