Re: [Boost-users] [proto] Wrapper compile error

Subject: Re: [Boost-users] [proto] Wrapper compile error
From: Eric Niebler (eric_at_[hidden])
Date: 2010-02-02 01:44:42

On 2/2/2010 3:40 PM, David A. Greene wrote:
> somewhere in the guts of proto there's an expectation that wrappers
> have one template argument.

Yes, it's proto::pod_generator. You have this:

// Expression wrapper
template<class Expr, class Dummy = boost::proto::is_proto_expr>
struct Wrapper {
   BOOST_PROTO_EXTENDS(Expr, Wrapper<Expr>, Domain)
};

...

struct Domain :
   boost::proto::domain<boost::proto::pod_generator<Wrapper > > {};

pod_generator is documented as taking a single template template 
parameter, as follows:

template<template<typename> class Extends>
struct pod_generator

The extra template parameter to Wrapper is not strictly necessary 
AFAICS, so perhaps you can just drop it. If not, you can define your own 
generator. It just needs to be a unary function object. See how 
pod_generator is defined.

HTH,

-- 
Eric Niebler
BoostPro Computing
http://www.boostpro.com