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<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">[…] there is little incentive to do that before modules get merged.<o:p></o:p></li></ul>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Right. Which is why we shouldn’t ask for perfection of the ecosystem before we get started.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>From:</b> tooling-bounces@open-std.org <tooling-bounces@open-std.org>
<b>On Behalf Of </b>Corentin<br>
<b>Sent:</b> Thursday, January 10, 2019 1:18 PM<br>
<b>To:</b> WG21 Tooling Study Group SG15 <tooling@open-std.org><br>
<b>Subject:</b> Re: [Tooling] Modules naming<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">It is a chicken and egg problem.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Integrating modules in build systems will be a tedious endeavor - especially in meta build systems,<o:p></o:p></p>
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<p class="MsoNormal">and there is little incentive to do that before modules get merged.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">It would be rather inconvenient to realize modules are not reasonably consumed by build system _after_ the IS is published.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">While having large modularized projects and build systems would be nice, it's a luxury we don't seem to have.<o:p></o:p></p>
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<p class="MsoNormal">And I think taking a long look at module toolability (both in term of current tools. and in term of the 10 years goals/hopes this group has for tooling) falls in SG15 purview.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">While my own experience is limited, I trust this group has enough build system experience and knowledge to foresee eventual issues and correct for them.<o:p></o:p></p>
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<p class="MsoNormal">We can also extrapolate from the well-known issue of headers name collision that exists and the guidelines that arose from that. <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">It is important to be explicit about what we mean when we say "implementation experience" when talking about modules because they exist at the border between language and tools<o:p></o:p></p>
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<p class="MsoNormal">and having compiler implementation experience isn't the whole story.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Thu, 10 Jan 2019 at 21:39 JF Bastien <<a href="mailto:cxx@jfbastien.com">cxx@jfbastien.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">On Thu, Jan 10, 2019 at 11:52 AM Corentin <<a href="mailto:corentin.jabot@gmail.com" target="_blank">corentin.jabot@gmail.com</a>> wrote:<br>
><br>
> I suspect it will be a while (several years) before we start to see large projects transitioning fully to modules and consumed as such by tools doing automatic dependency scanning etc.<br>
> My understanding is that there is little large scale implementation experience as far as tooling and build systems are concerned ( there is plenty _compilers_ implementation experience, and some build system implementation (and usage of modules) experience
- mostly in build2).<br>
<br>
Given your statement above, why is it useful for SG15 to discuss<br>
enforcing mapping? Specifically, how will that discussion be grounded<br>
in facts? It seems to me like facts need a compiler implementation,<br>
and a codebase to try it out on. Feel free to talk about hypotheticals<br>
all you want, but in this case code wins.<br>
<br>
I think you want to refocus your approach: what are you trying to<br>
achieve? What's the advantage that SG15 has, which the modules SG and<br>
now EWG don't have? How can SG15 contribute module's success?<br>
<br>
<br>
> On Thu, 10 Jan 2019 at 18:47 JF Bastien <<a href="mailto:cxx@jfbastien.com" target="_blank">cxx@jfbastien.com</a>> wrote:<br>
>><br>
>> On Thu, Jan 10, 2019 at 6:53 AM Corentin <<a href="mailto:corentin.jabot@gmail.com" target="_blank">corentin.jabot@gmail.com</a>> wrote:<br>
>> ><br>
>> > Hello.<br>
>> > I would like to suggest two modules related proposals that I think SG15 should look at.<br>
>> ><br>
>> > - Compiler enforced mapping between module names and module interface file (resource) name.<br>
>><br>
>> Why does SG15 need to do this, versus someone implementing it in an<br>
>> open-source toolchain, trying it out, and bringing what using it<br>
>> taught them to SG15?<br>
>><br>
>><br>
>> > Currently, modules interfaces can be declared in any file - which makes dependency scanning more tedious than it needs to be and have performance implications<br>
>> > (The build system needs to open all files to gather a list of modules) - notably when the build system tries to start building while the dependency graph isn't yet complete.<br>
>> ><br>
>> > Tools ( ide, code servers, indexers, refactoring) may also greatly benefit from an easier way to locate the source file which declares a module.<br>
>> ><br>
>> > The specifics of the mapping are open to bikeshedding. However, I think we would have better luck sticking to something simple like <module identifier> <=> <file name>.<extension><br>
>> > (The standardese would mention resource identifier rather than filename)<br>
>> ><br>
>> > - A standing document giving guidelines for modules naming.<br>
>> ><br>
>> > The goal is to take everything the community had to learn the hard way about header naming over the past 30 years and apply it to modules by providing a set of guidelines<br>
>> > that could be partially enforced by build system vendors.<br>
>> > Encouraging consistency and uniqueness of module identifiers across the industry is I think a necessary step towards sane package management.<br>
>> > Note that the standard requires uniqueness of modules identifiers within (the standard definition of) a program but says little about a way to ensure this uniqueness.<br>
>> ><br>
>> > Here is a rough draft of what I think would be good guidelines, partially inspired by what is done by other languages facing similar issues.<br>
>> ><br>
>> > Prefix module names with an entity and/or a project name to prevent modules from different companies, entities and projects of declaring the same module names.<br>
>> > Exported top-level namespaces should have a name identic to the project name used as part of the name of the module(s) from which it is exported.<br>
>> > Do not export multiple top-level namespaces<br>
>> > Do not export entities in the global namespace outside of the global module fragment.<br>
>> > Organize modules hierarchically. For example, if both modules example.foo and example.foo.bar exist as part of the public API of example, example.foo should reexport example.foo.bar<br>
>> > Avoid common names such as util and core for module name prefix and top-level namespace names.<br>
>> > Use lower-case module names<br>
>> > Do not use characters outside of the basic source character set in module name identifiers.<br>
>> ><br>
>> > My hope is that these 2 proposals (whose impact on the standard is minimal) would make it easier for current tooling to deal with modules<br>
>> > while making possible for example to design dependency managers and build systems able to work at the module level.<br>
>> ><br>
>> > I'd love to gather feedback and opinions before going further in that direction.<br>
>> > Thanks a lot!<br>
>> ><br>
>> > Corentin<br>
>> ><br>
>> > PS: For a bit of background, I talked about these issues there<br>
>> ><br>
>> > <a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcor3ntin.github.io%2Fposts%2Fmodules_mapping%2F&data=02%7C01%7Cgdr%40microsoft.com%7C50b0d4ca0e2a470bb25608d6774119dc%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636827518827616635&sdata=4ahioISF0bLasCdpTd%2B1Coe0x0pP1aZnUlWMoY2LE%2Bk%3D&reserved=0" target="_blank">
https://cor3ntin.github.io/posts/modules_mapping/</a><br>
>> > <a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcor3ntin.github.io%2Fposts%2Fmodules_naming%2F&data=02%7C01%7Cgdr%40microsoft.com%7C50b0d4ca0e2a470bb25608d6774119dc%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636827518827626648&sdata=0jGMXRsqHoGDOUgZHJYrq1n2gLQTDAvQBxsuQuZUs7k%3D&reserved=0" target="_blank">
https://cor3ntin.github.io/posts/modules_naming/</a><br>
>> ><br>
>> ><br>
>> > _______________________________________________<br>
>> > Tooling mailing list<br>
>> > <a href="mailto:Tooling@isocpp.open-std.org" target="_blank">Tooling@isocpp.open-std.org</a><br>
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