[Boost-users] Re: aliasing make_tuple

From: Pablo Aguilar (pablo.aguilar_at_[hidden])
Date: 2005-04-18 19:44:30

How about using Boost.Preprocessor and have it write the 10 overloads for 
you?

There should be examples available for you to look at (sorry, wouldn't know 
how to write it by heart, I'm still fairly new to Boost.PP and have to 
constantly look at the docs)

Pablo Aguilar

"Davi de Castro Reis" <davicastro_at_[hidden]> wrote in message 
news:426453CE.3060804_at_terra.com.br...
> Hi,
>
> I have a class where I use a tuple as input for some of my methods. The 
> reason for this is that the number of parameters for these methods is a 
> compile-time variable. See sample code below.
>
> template <uchar nparams, typename T1, typename T2 = none, typename T3 = 
> none ...>
> class A
> {
> void f(boost::tuple<char, char, ..., char>);
> }
>
> So users can do something like
>
> A a<3, char, char, char>
> a.f(make_tuple('a', 'b', 'c');
>
> The problem is that make_tuple is not a nice name, since it does not 
> reflect the semantics of the parameter. Suppose I would like to call it 
> key, so I can call
>
> A a<3, char, char, char>;
> a.f(key('a', 'b', 'c'));
>
> So, in my context, everything gets much more clear. Does someone know an 
> elegant way of doing this? As I can thing, the only way I can do it, is to 
> create a templatized free function called key, for which I will need to 
> write 10 overloads (the max number of nparams, and also boost tuple, if I 
> am not mistaken).
> Besides being a rather ugly solution, I will need to pay two copies of my 
> objects before sending them to the f() method (with make_tuple I pay only 
> one copy, which is also suboptimal, but, anyways...).
>
> Using #define is not an option since key is a very common name  (the class 
> is in a namespace). Ugly names such as MY_LIBRARY_KEY() are not a very 
> nice also.
>
> Well, any tips? Solutions involving boost::mpl would be the best, but I 
> couldn't find none.
>
> []s
> Davi de Castro Reis