version identifier hygiene

[Ali Çehreli via Digitalmars-d]

Moving from digitalmars.D.Learn...

tl;dr

It seems to be a good guideline to always name-mangle your version 
identifiers with the package (and module) name. Otherwise, you will risk 
confusions and conflicts on the build line.

Ali

On 01/16/2017 11:23 PM, Jacob Carlborg wrote:
> On 2017-01-16 21:04, Ali Çehreli wrote:
>> It is plausible to compile and link the sources of multiple packages on
>> the same command line at the same. (I'm not sure whether this is
>> required for e.g. LLVM's link-time optimization (LTO) but I think it
>> helps the compiler as well.)
>>
>> The trouble is, the version identifiers used by one package may look
>> strange on the command line and even contradict with another package's:
>>
>>     dmd -version=use-fibers a/a.d b/b.d
>>
>> use-fibers? Who is using fibers? Does it have any effect on the other
>> package as well?
>>
>> So, I think it's a good idea to name-mangle version identifiers with
>> prefixed package names (a-use-fibers instead of use-fibers):
>>
>>     dmd -version=a-use-fibers a/a.d b/b.d
>>
>> What do you think?
>>
>> Is there a way of managing this from the outside? I couldn't do this for
>> a package by introducing a new file that "translates" to what it
>> understands:
>>
>> version (a-use-fibers) {
>>     version=use-fibers;
>> }
>>
>> I tried putting it in a module and importing by all sources of package
>> 'a' but version did not have affect on the modules that imported it.
>
> Yeah, I think it only applies to the module it's set in.
>
>> String mixins would probably work but it already feels too intrusive to
>> "fix" third party packages like that.
>
> I don't think it's possible to fix from the outside. I would rather see
> that the library is adopted for that. Or even better using some kind of
> config file. With Dub it's possible to generate something like a config
> file with preGenerateCommands. That config file could look something like:
>
> module liba.config;
>
> version (liba_use_fibers)
>     enum useFibers = true;
> else
>     enum useFibers = false;
>
> Then the library would use "static if" instead of "version" to pick the
> correct implementation.
>
> Or if the user of the library could supply the config file from the
> beginning then no version statements are needed. Not sure if that's
> possible though.
>