Path: ...!3.eu.feeder.erje.net!feeder.erje.net!weretis.net!feeder8.news.weretis.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: Help requested with P99-based macro to create Wayland listeners
Date: Wed, 10 Apr 2024 11:44:58 -0700
Organization: A noiseless patient Spider
Lines: 82
Message-ID: <uv6mna$14d6r$1@dont-email.me>
References: <pan$3770d$7f0531e6$76520fa1$2c09330e@invalid.invalid>
 <86ttka1p61.fsf@linuxsc.com>
 <pan$325a1$29dc1a44$271afe6a$307a257b@invalid.invalid>
 <uv46mg$e1e0$1@dont-email.me>
 <pan$57aa8$bcee1756$62f53bf3$9223a50a@invalid.invalid>
 <uv5kpk$s1fr$1@dont-email.me> <9kxRN.169894$t8cc.141699@fx06.iad>
 <uv696j$1108s$1@dont-email.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Injection-Date: Wed, 10 Apr 2024 20:44:59 +0200 (CEST)
Injection-Info: dont-email.me; posting-host="1e0154287d270c974cd6798ddf950547";
	logging-data="1193179"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1+QOqp2kRI2ibzRPs7N+8/AKzsXleCe1Hw="
User-Agent: Mozilla Thunderbird
Cancel-Lock: sha1:pEPmvzVY0/H/Co22IYRcgmarT2A=
In-Reply-To: <uv696j$1108s$1@dont-email.me>
Content-Language: en-US
Bytes: 4578

On 4/10/2024 7:54 AM, David Brown wrote:
> On 10/04/2024 16:26, Scott Lurndal wrote:
>> David Brown <david.brown@hesbynett.no> writes:
>>> On 09/04/2024 22:20, Blue-Maned_Hawk wrote:
>>>> David Brown wrote:
>>>>
>>>>> On 09/04/2024 20:17, Blue-Maned_Hawk wrote:
>>>>>> Tim Rentsch wrote:
>>>>>>
>>>>>>> What is it that you want to accomplish?
>>>>>>
>>>>>> As i stated in the subject line, i am trying to create a macro to
>>>>>> create Wayland listeners.
>>>>>>
>>>>>>
>>>>> Assume, for the sake of argument, that no one knows or cares anything
>>>>> about Wayland or listeners.
>>>>
>>>> <https://xkcd.com/1432/>
>>>>
>>>>> You are trying to use a set macros to expand to some code.  Start by
>>>>> showing what code you want to get from examples of using your macros -
>>>>> then people can try to help get the macros right.
>>>>
>>>> MAKE_LISTENER(wl_registry, global, global_remove);
>>>>
>>>> →
>>>>
>>>> static const struct wl_registry_listener wl_registry_listener = { 
>>>> .global
>>>> = callback_wl_registry_global, .global_remove =
>>>> callback_wl_registry_global_remove };
>>>
>>> #define _get_6th_arg(_1, _2, _3, _4, _5, _arg, ...) _arg
>>> #define _fe_0(_global, _call, ...)
>>> #define _fe_1(_global, _call, x) _call(_global, x)
>>> #define _fe_2(_global, _call, x, ...) _call(_global, x) _fe_1(_global,
>>> _call, __VA_ARGS__)
>>> #define _fe_3(_global, _call, x, ...) _call(_global, x) _fe_2(_global,
>>> _call, __VA_ARGS__)
>>> #define _fe_4(_global, _call, x, ...) _call(_global, x) _fe_3(_global,
>>> _call, __VA_ARGS__)
>>> #define expand_macro_for_each(_global, _macro, ...) \
>>>      _get_6th_arg("ignored", __VA_ARGS__, \
>>>      _fe_4, _fe_3, _fe_2, _fe_1, _fe_0)(_global, _macro, __VA_ARGS__)
>>>
>>>
>>>
>>> #define MAKE_LISTENER(object_type, ...) _make_listener(object_type,
>>> __VA_ARGS__)
>>> #define _listener_entry(_global, _field) , . _field = callback_ ##
>>> _global ## _ ## field
>>> #define _make_listener(object_type, first_field, ...) static const 
>>> struct \
>>>      object_type ## _listener object_type ## _listener = { \
>>>      .first_field = callback_ ## object_type ## _ ## first_field \
>>>      expand_macro_for_each(object_type, _listener_entry, __VA_ARGS__) \
>>>      }
>>>
>>
>> Frankly I'd reject that code in any code review request.
> 
> I normally like code to be so clear that comments about how it works are 
> unnecessary.  But I think for something like this, a few comments would 
> be helpful!
> 
> When doing this kind of messing around with advanced preprocessing, it's 
> useful to have a set of re-usable macros that can be written and 
> documented once.  The "expand_macro_for_each" macro and its parts is 
> partly there, and once that is in place and accepted, the rest is a lot 
> smaller step to accept in a code review.
> 
> But this is code to help the OP get his macro generations working. 
> Whether he likes it, rejects it, or uses it for inspiration is up to him.
> 
> 

The OP needs a deep read of the chaos lib:

https://github.com/rofl0r/chaos-pp

Might help... ? ;^)