Re: [Boost-users] Question about Any usage

From: Christian Holmquist (c.holmquist_at_[hidden])
Date: 2008-04-25 19:22:05

On 24/04/2008, John Femiani <JOHN.FEMIANI_at_[hidden]> wrote:
>
>  >
>  > On Wed, Apr 23, 2008 at 05:06:58AM +0000, Ryan Gallagher wrote:
>  > > Jeffery Cavallaro <jcavalla <at> google.com> writes:
>  > > [...]
>  > > > For example, if I wanted to a program to spit out all of
>  > its options
>  > > > to standard out, there doesn't seem to be any hooks to extract an
>  > > > Any value in a generic way (e.g., as a string).
>  > >
>  > > Okay, this isn't exactly generic and only addresses this
>  > specific case
>  > > for the issue that you brought up, but for program_options
>  > where you
>  > > normally just have a limited number of types I've used:
>  >
>  > I've done something similar as well.  If you have a lot of
>  > types, and you want support for vectors of those types, you
>  > may want to look at the boost preprocessor macro library:
>  >
>
>
>
> So, could somebody write a visit_any function / macro, or do we need to
>  do some kind of hack each time. I am imagining a visit_any function that
>  takes an mpl vector of types as an argument ...
>
>

This has been discussed many times in the dev list I think, search for
'any visitor' in the archives.

I posted a small utility some time ago as a base for discussion. It
was named badly (any_variant), since I needed a visitor mechanism
identical to the one in boost::variant , maybe it could be of some use
to someone =)

http://lists.boost.org/Archives/boost/2007/09/127126.php

/ Christian

>  -- John Femiani
>
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