Re: [boost] If boost::fusion is the hammer, then what's the nail?

From: Steven Watanabe (steven_at_[hidden])
Date: 2006-12-14 15:59:58

AMDG

Weapon Liu wrote:
> I think this is the right place to ask this question.
> As cool as boost::fusion is, there's still one question that bothers me, 
> that is, if boost::fusion is the hammer, then what's the nail?
>
> I sure know that it's generic( more so than boost::tuple) and it's 
> complete( with a bundle of algorithms and cool utilities), and it seems 
> that it "solves" some problem quite well( when I read the documents).
>
> However, I found it bothering that the documents didn't even mention one 
> real-world application( boost libs aside).
>
> Based on my experience, the most frequent scenarios where 
> boost::tuple/fusion is useful are those where one needs a 
> generated-on-the-fly struct for holding return values bundle, or where 
> one needs to return multiple values transparently( well, nearly so), 
> just like those lua does.
>
> Other than that, I can't really imagine a scenario where this kinda 
> stuff kicks butts. The biggest disadvantage of boost::fusion, I think, 
> is that the size of it is known and fixed at compile time, which renders 
> it not so qualified as a truly heterogeneous container.
>
> And by the bye, that it can be used to build a handy pseudo-struct  that 
> enables full introspection really is a good and fancy feature. However, 
> there's something fundamentally irremediable of it, that is, it can't be 
> used to build a full-fledged class( rather than a POD-struct), which, I 
> think, will too reduce its usefulness w.r.t. this kinda situations.
>
> I personally very like this fancy facility, and that's why I present 
> these mumbles here to annoy you guys( if so, my apologies go here:-))
> Any comments?
>
>   

I needed basically the functionality of fusion::map to implement a table 
of function
pointers.  I can't use fusion for this though because I rely on POD 
initialization.

In Christ,
Steven Watanabe