How to retrieve instance by name?

[project2501]

Hi,

  I was looking for a way to retrieve an existing component instance by name that was instantiated with @Instantiate?

Is this possible?

thanks.

[Thomas Calmant]

Hi,

Indeed, the iPOPO core service misses a get_instance(name) method.

The idea behind this is to ensure that the instance of an isolated component (providing no service)

won't be accessible by anything but the class which instanciated the component.

This is subject to debate, mostly because the implementation can't ensure that nobody

will access the dictionary holding all references.

As a result, a get_instance(name) method could be added to the core service, pretty easily.

Although, if the component provides a service, the component object will be this service,

and iPOPO automatically adds it an "instance.name" property.

The following snippet does the trick, if the component provides at least one service:

svc_ref = context.get_service_reference(None, "(instance.name=some-name)")

component = context.get_service(svc_ref)

Regards,

Thomas

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[Darren G]

Thanks. Because the situation I run into is I like to use my specification namespace name as my instance names when using @Instantiate.

That instance gets injected where it's needed.

If I then create a new instance from outside the framework I can't use the same name and have to them create a second redundant instance to use outside the framework as I can't retrieve the one the framework holds.

Can I use @Instantiate without a name?

[Thomas Calmant]

2017-02-23 21:23 GMT+01:00 Darren G <darre...@gmail.com>:

Thanks. Because the situation I run into is I like to use my specification namespace name as my instance names when using @Instantiate.

That instance gets injected where it's needed.

If I then create a new instance from outside the framework I can't use the same name and have to them create a second redundant instance to use outside the framework as I can't retrieve the one the framework holds.

OK, I see.

 

Can I use @Instantiate without a name?

No, but maybe you can kill the previous instance, if necessary.

I'll add a get_instance(name) method to the core service this weekend, as I'll (finally) have some time to work on the project.

 

[Darren G]

Ok. Thanks. I guess that will help support a singleton pattern and it will be up to the implementor to ensure correct behavior internally.

--

[Thomas Calmant]

If you require a component factory to only have one component instance at a time, no matter its name, you can use the SingletonFactory decorator [1].

With the get_instance(name) method, it should work as you want.

[1] https://ipopo.readthedocs.io/en/latest/refcards/ipopo_decorators.html#pelix.ipopo.decorators.SingletonFactory

[Thomas Calmant]

This issue corresponding to this discussion can be seen at:

https://github.com/tcalmant/ipopo/issues/74

[project2501]

Thomas,

   I really appreciate this. Fantastic. Thank you.

Darren

On Saturday, February 25, 2017 at 9:41:19 AM UTC-5, Thomas Calmant wrote:

This issue corresponding to this discussion can be seen at:

https://github.com/tcalmant/ipopo/issues/74

2017-02-23 22:17 GMT+01:00 Thomas Calmant <thomas....@gmail.com>:

If you require a component factory to only have one component instance at a time, no matter its name, you can use the SingletonFactory decorator [1].

With the get_instance(name) method, it should work as you want.

[1] https://ipopo.readthedocs.io/en/latest/refcards/ipopo_decorators.html#pelix.ipopo.decorators.SingletonFactory

2017-02-23 21:47 GMT+01:00 Darren G <darre...@gmail.com>:

Ok. Thanks. I guess that will help support a singleton pattern and it will be up to the implementor to ensure correct behavior internally.

On Feb 23, 2017 3:37 PM, "Thomas Calmant" <thomas....@gmail.com> wrote:

2017-02-23 21:23 GMT+01:00 Darren G <darre...@gmail.com>:

Thanks. Because the situation I run into is I like to use my specification namespace name as my instance names when using @Instantiate.

That instance gets injected where it's needed.

If I then create a new instance from outside the framework I can't use the same name and have to them create a second redundant instance to use outside the framework as I can't retrieve the one the framework holds.

OK, I see.

 

Can I use @Instantiate without a name?

No, but maybe you can kill the previous instance, if necessary.

I'll add a get_instance(name) method to the core service this weekend, as I'll (finally) have some time to work on the project.

 

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