On 15.06.2020 8:45, Serhiy Storchaka wrote:
> 14.06.20 23:45, Ivan Pozdeev via Python-Dev пише:
>> 1. The documentation clearly says that it's supported depending on OS flavor -- so if I want to know if I can supply it, I need to rather
>> check `os.name`. Those members are thus redundant.
>>
>>      If the distinction is finer than os.name then I'd need some other, case-specific check depending on what the distinction is;
>> alternatively, I could check the function's signature in its metadata if the support is reflected in it.
>
> Yes, it is finer than os.name. It can depend on the kernel or libc version (and we do not know which versions are required on every
> platform), and there are a lot of platforms besides the main three. The user should not be expert in all platforms on which his program
> potentially can be ran.
>
> The function's signature is the same on all platforms. Just on some platforms only default value can be passed (None for dir_fd) or only
> specific types of argument is accepted (path-like, but not int).

Then a single boolean flag is clearly not enough. Compare: in https://docs.python.org/3/library/resource.html , the set of present RLIMIT_*
members shows which rlimits are available in the specific OS.

So I guess you want some similar pointers that would show which relevant #define constants (or other C-level entities that govern the
availability) were present at the time of compilation.
If availability is rather governed by a runtime than compile-time check, then something to perform the same check should be introduced; the
distinction from .supports_stuff is it would be named after the check and completely decoupled from any functions that might be affected by
the check.


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> Regards,
> Ivan
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