Re: [Boost-users] boost::bind and Motif

Subject: Re: [Boost-users] boost::bind and Motif
From: Igor R (boost.lists_at_[hidden])
Date: 2012-05-02 09:14:57

> I just tried to use boost::bind to create a function pointer from an object
> method to define it as a Motif callback function:
>
> class AnimationController {
> public:
> Â  Â void timerCB( XtPointer, XtIntervalId* );
> Â  Â void startTimer() {
> Â  Â  Â  Â this->mTimeout = XtAppAddTimeOut( this->mAppContext,
> ANIMATION_TIMESTEP,
> Â  Â  Â  Â  Â  Â  Â  Â boost::bind( &AnimationController::timerCB, this ), NULL );
> Â  Â }
> Â  Â ...
> };
>
> For the definition of the Motif function:
> XtIntervalId XtAppAddTimeOut(
>    XtAppContext     /* app_context */,
>    unsigned long     /* interval */,
> Â  Â XtTimerCallbackProc /* proc */,
>    XtPointer         /* closure */
> );
>
> with
>
> typedef void (*XtTimerCallbackProc)(
>    XtPointer         /* closure */,
> Â  Â XtIntervalId* Â  Â /* id */
> );
>
> But I get the following error:
>
> ../AnimationController.cpp: In member function 'void
> geo::AnimationController::startTimer()':
> ../AnimationController.cpp:193: error: cannot convert
> 'boost::_bi::bind_t<void (&)(void*, XtIntervalId*), boost::_mfi::dm<void
> ()(void*, XtIntervalId*), geo::AnimationController>,
> boost::_bi::list1<boost::_bi::value<geo::AnimationController*> > >' to 'void
> (*)(void*, XtIntervalId*)' for argument '3' to 'XtIntervalId
> XtAppAddTimeOut(_XtAppStruct*, long unsigned int, void (*)(void*,
> XtIntervalId*), void*)'

Bind creates a function object, while XtAppAddTimeOut expects a
function pointer, as you mentioned.
You can define a static member function that matches
XtTimerCallbackProc signature, and pass it without bind.