| Share data between plugins? [message #328721] |
Mon, 02 June 2008 15:08  |
Eclipse User |
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Hi there,
what is the right design pattern to achieve this:
I have two plugins. The one implements some stateless action within
Eclipse (i.e. GMF Layout Provider).
Now I want to add some state (some internal data) and make my other
plugin listen to changes to that data.
Unfortunately I do not know how to access the instance of the first
plugin that is used by Eclipse. There is no specific accessor method,
like for views and editors.
I could only create a completely new instance via the
ConfigurationElement for that plugin but that would not give me the
correct instance that stores the required data.
Is there any pattern to do that? Seems like a common problem to me.
My idea is to implement the singleton pattern to get the one and only
instance of the first plugin's classes by static references. Is this the
only way to do it?
I can't be sure how Eclipse handles the objects internally. Maybe it
creates a new instance of the plugin every time the action is called...
then this static reference would change every time and a listener of one
of the instances would not help...
Any ideas?
Hauke
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| Re: Share data between plugins? [message #328741 is a reply to message #328721] |
Tue, 03 June 2008 09:55  |
| Eclipse User |
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Originally posted by: eclipse-news.rizzoweb.com
Hauke Fuhrmann wrote:
> Hi there,
>
> what is the right design pattern to achieve this:
>
> I have two plugins. The one implements some stateless action within
> Eclipse (i.e. GMF Layout Provider).
> Now I want to add some state (some internal data) and make my other
> plugin listen to changes to that data.
>
> Unfortunately I do not know how to access the instance of the first
> plugin that is used by Eclipse. There is no specific accessor method,
> like for views and editors.
> I could only create a completely new instance via the
> ConfigurationElement for that plugin but that would not give me the
> correct instance that stores the required data.
>
> Is there any pattern to do that? Seems like a common problem to me.
>
> My idea is to implement the singleton pattern to get the one and only
> instance of the first plugin's classes by static references. Is this the
> only way to do it?
> I can't be sure how Eclipse handles the objects internally. Maybe it
> creates a new instance of the plugin every time the action is called...
> then this static reference would change every time and a listener of one
> of the instances would not help...
>
> Any ideas?
If you look at how the Activator classes are usually implemented, they
maintain a static reference to the "default" instance, which is set to
"this" in the start() method. They provide a public accessor to get the
reference. This works because each plugin will only be start()ed once.
See org.eclipse.core.resources.ResourcesPlugin.getPlugin() for an example.
Once you have a reference to the plugin class, it can manage references
to other shared data that you need to access from elsewhere.
Hope this helps,
Eric
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