Custom class as input/output parameter in plug-in

Replies to This Discussion

Permalink Reply by David Rutten on January 27, 2011 at 12:59pm

Hi Emilio,

 

not entirely correct. Or rather, not the best way to approach this.

 

The first thing you'll need to do is write your own data type and make sure it implements IGH_Goo (or derives from GH_Goo<T>). This is probably the hardest task, but it is explained in some detail in the Grasshopper SDK docs (look for the "Simple Data Types" topics in the Examples section).

 

Once you have your own data type, you could choose to use the Generic parameter to handle it. This will prevent you from storing persistent instances of your data anywhere. If you want to have a parameter that can specifically handle your data type, you'll need to write that as well. You can derive from GH_Param<T>, where T is your new data type. Or you can derive from GH_PersistentParam<T> if you want the ability to store local instances of your data.

 

Finally, to use your new parameter in a component you need to construct it yourself and pass it to the pManager.RegisterParam() method in RegisterInputParams() and RegisterOutputParams() calls. It is generally a bad idea to add or remove inputs and outputs from a component at a later stage.

 

--

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Emilio Morello on January 27, 2011 at 3:33pm

Hi David,

 

I think I'll try to keep that as simple as possible:

IGH_Goo and Generic parameters

( If I have understood your reply correctly ... )

 

Thanks a lot !

Emilio

 

Permalink Reply by Emilio Morello on January 28, 2011 at 10:28am

OK, implementing IGH_Goo and using Generic parameters

seems to work.   :)

But I have another question.

How to set up a component to export a List ?

I have to export a List of NurbsCurve

and I have not been able to figure how to make it work.

Using    Register_GenericParam()   does not raise errors

in the component but linking the output

to a Crv component raises an error in the Crv, saying it cannot

convert a Goo into a curve

Using   Register_CurveParam()  raises an error from the component

complainig that a List is not a curve.

 

What have I to do to export a List ?

 

Emilio

 

Permalink Reply by David Rutten on January 28, 2011 at 2:17pm

Hi Emilio,

 

exporting lists means calling the DA.SetDataList from within your SolveInstance method.

 

Are you using SetData() or SetDataList()?

 

--

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Emilio Morello on January 28, 2011 at 2:45pm

Aaaaaah ... I thought it should have been something obvious !    ;)

... and _obviously_ I was using SetData()

 

Works fine with SetDataList().

 

Thanks again David !

Have a nice weekend.

Emilio