[Haskell-cafe] Feedback on FFI bindings for C++ library

[kudah]

I'd suggest to first look at how other C++-bindings for haskell are
implemented. e.g. wxHaskell is the most mature Haskell C++ binding out
there. hogre tries to generate bindings from headers. And a number of
(rather minimal) bindings to some libs were made as part of Nikki and
the Robots.

On Thu, 17 Jan 2013 18:48:02 +0100 Nathan Hüsken
<nathan.huesken at posteo.de> wrote:

> Hey,
> 
> I would like to write FII bindings in haskell for cocos2d-x
> (http://www.cocos2d-x.org/), which is a C++ library.
> 
> Since I have little experience with this, I would like some feedback
> before I discover that concept is bad half way.
> 
> In cocos2d there is a base class with much functionality: CCNode
> Many classes derive from it (i.E. CCLayer) and use the virtual
> functions of CCNode (i.E. setPosition).
> 
> How do I map this to haskell?
> 
> The general Idea:
> 
> I have a typeclass, in which everything that is derived from CCNode is
> an instance:
> 
>     class NodeDerived a where
>       toNode :: a -> Node
> 
>       setPosition :: a -> (Double,Double) -> IO ()
>       setPosition a pos = setNodePosition (toNode a) pos
> 
>     instane NodeDerived Layer where
>       toNode = layerToNode
> 
> and layerToNode :: Layer -> Node would be implemented in C++ as:
> 
>     CCNode* layerToNode(CCLayer* l) { return
> dynamic_cast<CCNode*>(l); }
> 
> This way I would have only to implement toNode for every class derived
> from CCNode and get all the functions CCNode defines.
> 
> What do you think if this Idea?
> How would you do it?
> 
> Thanks!
> Nathan
> 
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