| What kind of data can be sent thru extension point? [message #266400] |
Wed, 11 August 2004 04:43  |
Eclipse User |
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Originally posted by: purjo76.luukku.com
Hi!
I earlier asked a question about extension points
( http://dev.eclipse.org/newslists/news.eclipse.platform/msg26 446.html),
and got an answer to look for an example from EIMP project. Thank you for
Gilles for that hint!
Anyway, that seems not to be an good example... On my mind they are using
extension points in a bit weird way, i.e. instead of transfering data thru
the extension point they instantiate classes from the extension by using
newInstance()- method, and then make method calls directly with that
reference.
Now, my question is: are there any limitations when transferring data thru
the extension point? I mean, is it just a way to add new graphical
components to the existing plugins offering an extension point, or could I
use it also for some more "heavy" use i.e. for sending (lots of...)
streamable objects from extension point plugin to all extending plugins?
If this is possible, how could it be done? All examples of extension
points that I've found are just using them for adding some new UI
components to some other graphical UI plugin.
IŽve searched for many days now, but still I could not find any document
that would explain the usage of extension points for this kind of usage.
Could someone please tell me is it possible, or should I forget it?
Thanks already!
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| Re: What kind of data can be sent thru extension point? [message #266662 is a reply to message #266400] |
Thu, 12 August 2004 03:57  |
| Eclipse User |
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Originally posted by: purjo76.luukku.com
Purjo wrote:
IsnŽt there really anyone out there who knows the extension points from
the deep, and could enlighten me a bit..?
> Hi!
> I earlier asked a question about extension points
> ( http://dev.eclipse.org/newslists/news.eclipse.platform/msg26 446.html),
> and got an answer to look for an example from EIMP project. Thank you for
> Gilles for that hint!
> Anyway, that seems not to be an good example... On my mind they are using
> extension points in a bit weird way, i.e. instead of transfering data thru
> the extension point they instantiate classes from the extension by using
> newInstance()- method, and then make method calls directly with that
> reference.
> Now, my question is: are there any limitations when transferring data thru
> the extension point? I mean, is it just a way to add new graphical
> components to the existing plugins offering an extension point, or could I
> use it also for some more "heavy" use i.e. for sending (lots of...)
> streamable objects from extension point plugin to all extending plugins?
> If this is possible, how could it be done? All examples of extension
> points that I've found are just using them for adding some new UI
> components to some other graphical UI plugin.
> IŽve searched for many days now, but still I could not find any document
> that would explain the usage of extension points for this kind of usage.
> Could someone please tell me is it possible, or should I forget it?
> Thanks already!
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| Re: What kind of data can be sent thru extension point? [message #266722 is a reply to message #266662] |
Thu, 12 August 2004 10:57 |
| Eclipse User |
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Originally posted by: Chris_Laffra.ca.ibm.com
Sorry, I wrote a long essay on this, and then Windows XP crashed on me.
Eclipse is essentially one Java program with multiple classloaders.
The extension points function only as 'matchmakers'. They connect
plug-ins unknown to each other and load them all into the same VM.
Once you have a reference to a given class, you can do anything you
want to do.
So, just view extension points as a set of rules that the platform uses to
create classloaders and activate plug-ins. Once everything is running,
there is no control (other visibility of classes across plug-ins).
By adding a plug-in to your dependency list, you can also see all the
classes it declares, even without needing extension points. This is
how SWT and JFace work, for instance.
Read FAQ 86 at http://eclipsefaq.org to see how a plug-in can find
out all the others that contribute to a given extension point. In our
example, the local called 'obj' holds the pointer to the created
class instance, and you can cast it into a more specific type.
In summary, there are no limits.
Chris
"Purjo" <purjo76@luukku.com> wrote in message
news:cff7tp$iup$1@eclipse.org...
> Purjo wrote:
>
> Isn
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| Re: What kind of data can be sent thru extension point? [message #266724 is a reply to message #266400] |
Thu, 12 August 2004 11:02 |
| Eclipse User |
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Originally posted by: john.eclipsefaq.org
You can send arbitrary data to extensions from an extension point. The
extension will typically implement an interface defined by the extension
point. The extension point's plugin can then load the extensions from
the plugin registry (IConfigurationElement.createExecutableExtension),
and then pass any kind of data you like to the extension object. There
are no limitations.
--
Purjo wrote:
> Hi!
>
> I earlier asked a question about extension points
> ( http://dev.eclipse.org/newslists/news.eclipse.platform/msg26 446.html),
> and got an answer to look for an example from EIMP project. Thank you for
> Gilles for that hint!
>
> Anyway, that seems not to be an good example... On my mind they are using
> extension points in a bit weird way, i.e. instead of transfering data thru
> the extension point they instantiate classes from the extension by using
> newInstance()- method, and then make method calls directly with that
> reference.
>
> Now, my question is: are there any limitations when transferring data thru
> the extension point? I mean, is it just a way to add new graphical
> components to the existing plugins offering an extension point, or could I
> use it also for some more "heavy" use i.e. for sending (lots of...)
> streamable objects from extension point plugin to all extending plugins?
> If this is possible, how could it be done? All examples of extension
> points that I've found are just using them for adding some new UI
> components to some other graphical UI plugin.
>
> IŽve searched for many days now, but still I could not find any document
> that would explain the usage of extension points for this kind of usage.
> Could someone please tell me is it possible, or should I forget it?
>
> Thanks already!
>
>
>
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