Re: [boost] Egg 2nd request for reviews: Some comments

From: vicente.botet (vicente.botet_at_[hidden])
Date: 2008-04-06 16:58:34

----- Original Message ----- 
From: "shunsuke" <pstade.mb_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Sunday, April 06, 2008 9:10 PM
Subject: Re: [boost] Egg 2nd request for reviews: Some comments

> vicente.botet wrote:
>> Hi again,
>>
>> In the Quick start, I found this use of macros very odd
>>
>> egg::result_of_pipable<T_make_filtered>::type
>>     const filtered = BOOST_EGG_PIPABLE_L BOOST_EGG_POLY()
>> BOOST_EGG_PIPABLE_R;
>>
>> egg::result_of_pipable<
>>     egg::result_of_indirect<T_make_filtered const *>::type
>>> ::type
>>     const her_filtered = BOOST_EGG_PIPABLE_L
>> BOOST_EGG_INDIRECT(&make_filtered) BOOST_EGG_PIPABLE_R;
>>
>> Could you show what a user that do not use the macros needs to write. 
>> This
>> will surely help to understand why these macros a necessary.
>
> It was really odd.
> Fortunately, in a recent discussion,
> it is shown that those macros can be removed with a trivial patch.
> A newly proposed form is:
>
>     egg::static_<
>         result_of<T_pipable(T_make_filtered)>
>     >::type const filtered = {{}};
>
> How do you think about this form?

Well, there are no more macros, this is much better for me..
Sorry, I have missed the post. Could you give me the reference to this 
discussion?

>
>> It would be very nice if the docummentation contains links for the macros
>> the same way you have done for the specific notation.
>>
>> By the way I fond this link to specific notation very useful. Thanks for 
>> the
>> trick.
>
> Thanks.
>
>> I have no doubt that the use of bind expressions may be less readable 
>> than:
>> void quick_start_nest()
>> {
>>     int i6 = 6, i7 = 7;
>>     std::plus<int> plus;
>>     std::minus<int> minus;
>>
>>     int r =
>>     // Lv: 0     1          2
>>         // \x -> (\(y,z) -> plus(5, y(z, x)))
>>         egg::nest2(plus)(5, egg::nest2(_1_(_1))(_1_(_2), _0_(_1)))
>>             (i6)(minus, i7);
>>
>>     std::cout << r;
>> }
>>  Prints 6.
>>
>> But, do you really think that some one is able to read this without 
>> taking 5
>> minutes :-(. I think that you should start with more simple examples,
>> showing only a new feature and comparing with code without Egg.
>
> nestN was invented just two weeks ago.
> I must admit less explanation. And a simple example will be added with a 
> comparison.
> (Maybe I wanted to show this feature to lambda library authors.)
>
>> I like a lot your fuse/unfuse technique for emulating variadic functions.
>> Only this is enough to see in the implementation.
>
> Ok.
>
>> On the section The Return of the Monomorphic It would be greate to see 
>> the
>> compiler messages with and without Egg.
>
> I will.
>
>
> Regards,
>
> -- 
> Shunsuke Sogame

Best regards
_____________________
Vicente Juan Botet Escriba