Re: DSEL syntax, or opening the can of worms.

On 8/8/07, Rene Rivera <[email protected]> wrote:
> First I think we all agree that the Luabind DSEL syntax is "nicer" than
> the BPL syntax. Last night, something kept bothering me. The syntax
> dealing with namespaces/modules vs. the syntax for dealing with classes
> and inner classes are inconsistent with each other. Yet to me both deal
> with defining scopes, and members within those scopes. To take a simple
> example:
>
> namespace a
> {
>    int f();
>
>    struct A
>    {
>      void do();
>
>      struct B
>      {
>        void again();
>      };
>    };
> }
>
> In Luabind the binding declaration would look like:
>
> module(L)
> [
>    namespace_(L,"a")
>    [
>      def("f",&a::f),
>      class<a::A>("A")
>        .def("do",&a::A::do)
>        .scope
>        [
>          class_<a::A::B>("B")
>            .def("again",&a::A::B::again)
>        ]
>    ]
> ]
>
> That shows that 'module' and 'namespace_' use [] to bound the scope they
> define. But 'class' uses ".method" to chain the scope out as needed. And
> introduces the rather unintuitive, IMO, '.scope' to allow one "access"
> to the class scope. So I though, why not be consistent and use [] to
> define all scopes. Which leads to (removing the module/namespace
> destinction):
>
> namespace_(L,"a")
> [
>    def("f",&a::f),
>    class_<a::A>("A")
>    [
>      def("do",&a::A::do),
>      class_<a::A::B>("B")
>      [
>        def("again",&a::A::B::again)
>      ]
>    ]
> ]
>
> Which has a one-to-one correspondence with the C++ code.

Boost.Python code looks familiar to Python users:

class< X > ( "X" )
    .def( ... )
    .def( ... );

I guess that this was one the goals of the library. lang-binding is a
little bit different: it aims to provide different "back-ends". I
think it is impossible to come with a DSL, which will satisfy all
"back-end" developers and you are right: we should stick to one-to-one
correspondence with the C++ code.


-- 
Roman Yakovenko
C++ Python language binding
http://www.language-binding.net/

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