Transitioning std lib modules/packages

[Andrea Fontana via Digitalmars-d]

On Monday, 28 November 2016 at 13:51:13 UTC, Andrei Alexandrescu 
wrote:
> On 11/28/2016 08:42 AM, Andrea Fontana wrote:
>> On Monday, 28 November 2016 at 13:34:42 UTC, Andrei 
>> Alexandrescu wrote:
>>> On 11/28/2016 04:13 AM, Andrea Fontana wrote:
>>>> Hoping std.v2.stdio works and it's an alias to std.stdio.
>>>
>>> That doesn't work - how do you later make breaking changes to
>>> std.v2.stdio? We'd be missing the very point of doing this. 
>>> -- Andrei
>>
>> It's just an api level. When you need a breaking change all 
>> modules will
>> be updated to v3 as alias except the edited ones.
>>
>> V3 it just like a commit-id on github.
>
> I see - although that's an awesome idea for github, it seems 
> excessive to bump the version of the entire stdlib when we want 
> to transition one module or package of it. -- Andrei

It's just a simple tag. And I hope that breaking changes are not 
that frequent!
I think that on worst case there will be a new api level every 
dmd release. It just happens, but in this way it is managed in a 
better way. If needed we can use API_LEVEL_DMD_2071_3 as 
identifier. But IMO PHOBOS_API_LEVEL_2 makes more sense.

It would be really easy to mantain a back-compatibility. Just 
select the right api level, and you can still use new dmd 
version! Something similar really works fine with android 
api_level.