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Subject: [Boost-users] [fusion] Introspection of fused objects?
From: Rutger ter Borg (rutger_at_[hidden])
Date: 2010-02-17 08:44:49
Suppose I have a function object created on the basis of a sequence of fused
function objects, where I would like to do shuffle the call order on the
basis of some criterion.
template< typename SeqOfFused >
struct merge_fused {
merge_fused( SeqOfFused f ): m_functions( f ) {}
typedef void result_type;
template< int N, typename Seq >
void operator()( Seq& seq ) {
// normal dispatch call would be fusion::at_c<N>(m_functions)( seq );
if ( some case ) {
store seq for later use
} else {
call appropriate fused object with parts of stored stuff
}
}
SeqofFused m_functions;
// some state / memory specific to this group of fused objects
some_state m_state;
};
I'm doing a static cast to a superclass to get rid of the int N template
parameter, to make the merge_fused look exactly like a fused function
object. This works fine.
Storing stuff is what my question is about: is there any way to know the
type of Seq from its Fused counterpart? Looking at the code, the answer is
no, but perhaps there exists introspection code in fusion which I am unaware
of?
One solution would be to simply use static casting based on Seq in
operator(), but then my question would be: is that safe?
Thanks,
Rutger
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