Re: [Boost-users] Using boost::lambda::bind with std::transform

From: Kobi Cohen-Arazi (kobi.cohenarazi_at_[hidden])
Date: 2006-04-27 11:10:58

OK.

Next stage:
define a small helper:
    std::string removeConst (const std::string& s)
    {
        return s;
    }

// define a ptr to member func std::string::replace
            std::string & (std::string::*rep)(std::string::size_type,
                                              std::string::size_type, const
char *) = &std::string::replace;

// try to transform from
// but will not work. Compile fails
            std::transform(array.begin(), array(), std::back_inserter(tr),
                           boost::bind(rep,
                                       boost::bind(&removeConst,
boost::bind(&Foo::get, _1)),
                                       0, 5, ""));

// however that will work, so I probably missing something up there
            std::transform(array.begin(), array(), std::back_inserter(tr),
                           boost::bind(&removeConst, boost::bind(&Foo::get,
_1)));

Any idea?
Thanks,
Kobi.

On 4/27/06, Kobi Cohen-Arazi <kobi.cohenarazi_at_[hidden]> wrote:
>
> Hi Sebastian,
>
> Hmmm...... I think I know what the problem is ...
> Foo::get is const
>
> struct Foo{
>    std::string get() const { ... }
> };
>
> So it is not a good candidate to use in string::replace.
> I wonder how I can work around it, since I want to transform a _copy_ of
> that.
> Is there a way to create a copy on the fly? something like:
> ...bind(rep, std::string(bind(&Foo::get, _1)), 0, 5, ""));
>
> Thanks again for your insights.
> Kobi.
>
>
> On 4/27/06, Sebastian Redl <sebastian.redl_at_[hidden]> wrote:
> >
> > Kobi Cohen-Arazi wrote:
> >
> > > Hi,
> > >
> > > I've tried that, and I got a bunch of errors. I'm using boost::bind
> > > for that, not boost::lambda.
> > > Here is the error
> > >
> > > The following line:
> > > std::transform(array.begin(), array.end(), std::back_inserter(tr),
> > >   bind(&std::string::replace, bind(&Foo::get, _1), 0, 5, ""));
> > >
> > > generates:
> > > error: no matching function for call to 'bind(<unknown type>,
> > > boost::_bi::bind_t<const std::string&, boost::_mfi::cmf0<const
> > > std::string&, Foo>, boost::_bi::list1<boost::arg<1> > >, int,
> > > uint32_t&, const char [1])'
> >
> > Hmmm ... the <unknown type> is suspicious. The problem might be that
> > &std::string::replace is ambiguous, as it is overloaded. Try this:
> >
> > std::string & (std::string::*rep)(std::string::size_type,
> > std::string::size_type, const char *) = &std::string::replace;
> > std::transform(array.begin(), array.end(), std::back_inserter(tr),
> >   bind(rep, bind(&Foo::get, _1), 0, 5, ""));
> >
> > Sebastian Redl
> > _______________________________________________
> > Boost-users mailing list
> > Boost-users_at_[hidden]
> > http://lists.boost.org/mailman/listinfo.cgi/boost-users
> >
>
>