Re: [boost] Interest in DSL framework

From: Andy Little (andy_at_[hidden])
Date: 2006-08-14 16:10:45

"Joel de Guzman" wrote
> Andy Little wrote:
>> "Andreas Pokorny" wrote

>>>  template<typename EnableIfT>
>>>  struct
>>> rule<example_domain,bitor_tag,TYPE_WHICH_ENCODES_THE_EXPRESSION,C,EnableIfT>
>>>    : defined, mpl::true_
>>>  {
>>>     typedef TYPE_WHICH_ENCODES_THE_WHOLE_TREE result_type;
>>>     static result_type init(A const& a, B const& b) { return
>>> result_type(...); }
>>>  };
>>
>> I don't understand what these TYPE_WHICH_ENCODES_THE macros are, but can 't
>> you
>> use Boost.Typeof for this?
>
> IIUC, the "rule" specifies the result type (not deduces the
> result type). I think it's not a macro at all; it would rather
> be something like: "unspecified_type", or
> "you-define-your-type-here-and-ill-do-the-rest"

Well again I am probably not understanding it fully, but from  one of Andreas
posts higher in the thread:

get_result_type<add_tag,LeftT,RightT>

presumably could be implemented as:

template <typename LeftT, typename RightT>
struct get_result_type<add_tag,LeftT,RightT>
{
    typedef BOOST_TYPEOF_TPL(LeftT() + RightT()) type;
};

Anyway apologies if  I have missed the point.

regards
Andy Little