Re: [boost] [fusion] Trouble using BOOST_FUSION_ADAPT_ADT with boost::fusion::operator<

Subject: Re: [boost] [fusion] Trouble using BOOST_FUSION_ADAPT_ADT with boost::fusion::operator<
From: Nathan Ridge (zeratul976_at_[hidden])
Date: 2012-01-17 20:35:11

> > I'm attempting to adapt a third-party struct into a fusion sequence
> > using BOOST_FUSION_ADAPT_ADT to get access to a nice operator<.
> > Unfortunately compilation fails and I'm not sure if it's a bug or me
> > using the library incorrectly. As best I can read the error message, it
> > looks like the code is attempting to compare adt_attribute_proxy structs
> > instead of the values represented by these. Below is some code that
> > demonstrates the problem. Can anybody help me out?
> >
>
> You've bumped into a limitation of proxies. Fusion adapted ADTs do
> not have access to the actual L-values of the class members, but only
> through get and set. As such, it actually exposes proxy elements
> (adt_attribute_proxy) instead of the actual elements. The only thing
> you can do with these proxies is either to get the values or set the
> values:

Can't Fusion provide overloads for relational operators that compare
adt_attribute_proxy objects by comparing their values?

Regards,
Nate