2009/9/5 Martin Beckett <m...@mgbeckett.com>:
> [quote="Paul Martz"]If you can (obviously) change your code to understand
> instances of your new custom class, then I don't understand why you can't
> change your code to understand instances of ref_ptrs to your new custom
> class. Please explain this restriction further.
> I have a complicated navigation library with a few objects representing a
> position fix, GPS location, range+bearing observation etc. This library
> works !
>
> I want to re-use this in an OSG app. So I have written an adapter class where
> a position is now represented underneath by a PAT (which can be used directly
> in my OSG scene) but has the same name and implements the same set/get
> position operations as the existing position class.
>
> But since it is ultimately derived from Referenced it has a virtual dtor,
> cannot be create on the stack and cannot be copied with '='
>
> I can make the dtor public, but the more complicated part is implementing the
> copy operator - since it has to handle copying all the parent class of PAT.
>
> The alternative of having a bunch of interface functions to copy parameters
> to/from the scenegraph nodes into existing 'position' objects seemed a poor
> design.
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=17084#17084
>
>
>
>
>
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Hi Martin,
pimpl idiom may help you. That means you won't derive publicly from
PositionAttitudeTransform but have pointer to its implementation. This
is sometimes called a "has-a" relationship, rather than "is-a"
relationship. You may expose the same function interface with
PositionAttitudeTransform to outside world. Your methods will call
PAT's methods.
class MyAdapter
{
osg::ref_ptr<osg::PositionAttitudeTransform> m_sppat;
public:
MyAdapter() throw(std::bad_alloc)
: m_sppat(new osg::PositionAttitudeTransform)
{
}
// Transform methods
inline void setReferenceFrame(osg::ReferenceFrame rf) {
m_sppat->setReferenceFrame(rf); }
...
// PositionAttitudeTransform methods
inline void setPivotPoint(const osg::Vec3d& pivot) {
m_sppat->setPivotPoint(pivot); }
..
};
you may need to implement all methods you need. I don't think you will
need all public methods available in a PositionAttitudeTransform
(including those are inherited). I didn't compile it but something
like that should work.
Does this help you? The constructor may throw.
try
{
MyAdapter adapter;
// call your library function
} // PAT dies here
catch (std::bad_alloc&)
{
// out of memory
}
Ismail
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