Re: Boost.Lambda2 usage

From: Barry Revzin (barry.revzin_at_[hidden])
Date: 2021-03-28 20:47:31

On Sun, Mar 28, 2021 at 2:26 PM Emil Dotchevski via Boost <
boost_at_[hidden]> wrote:

> On Sun, Mar 28, 2021 at 10:50 AM Barry Revzin via Boost <
> boost_at_[hidden]> wrote:
> > Second, this library has name lookup issues. Here's a reduced example (
> > https://godbolt.org/z/z8oEqnTnG):
> >
> > #include <
> >
>
> https://raw.githubusercontent.com/pdimov/lambda2/develop/include/boost/lambda2/lambda2.hpp
> > >
> >
> > namespace N {
> >     struct Irrelevant { };
> >     void operator+(Irrelevant, Irrelevant);
> >
> >     int plus_one(int i) {
> >         using namespace boost::lambda2;
> >         return (_1 + 1)(i);
> >     }
> > }
>
> To successfully compile, this has to be:
>
> int plus_one(int i) {
>     using namespace std::placeholders;
>     using boost::lambda2::operator+;
>     return (_1 + 1)(i);
> }
>
> Note that it will not work if you say "using namespace boost::lambda2", you
> have to bring in each individual operator you need.
>

Yes, I understand all of that. But the point of this library is to provide
terse syntax for simple lambda expressions, and having to write
using-declarations for each operator in each scope that they are intended
to be used defeats the purpose.

Barry