Editions

[Steven Schveighoffer]

On Wednesday, 2 April 2025 at 12:52:59 UTC, Dukc wrote:
> On Tuesday, 1 April 2025 at 16:21:59 UTC, Atila Neves wrote:
>> https://github.com/atilaneves/DIPs/blob/editions/editions.md
>
>> Modules without a module declaration would be considered to be 
>> using the latest edition unless the default edition is 
>> specified explicitly with a command line argument.
>
> Why? I see no reason that they shouldn't behave like the 
> modules with editionless declaration at the top.

I think this might be my fault. In a long-ago review of the 
original editions, my concern was about *playground code*, or 
simply trying out the langauge.

Instead of having to first learn how to specify editions, one 
should be able to use the language as it is currently specified.

Basically, if you write a hello world program, or play with 
features, they should operate as documented, not as they were 2, 
3, 10 years ago.

My recommendation was that the compiler would *default* to using 
the current edition, if no edition was specified on the module. 
However, dub would behave differently and specify a default 
edition that is the pre-edition edition. This way, the thousands 
of dub configurations out there that existed before editions 
existed would default to the language at that level.

However, it seems this proposal goes a step further, and I agree, 
a confusing one. It is not hard to evolve playground code into a 
level that requires adding module declarations. I don't see why 
these need to be for the OG edition.

I think the default edition if none is specified should always be 
the latest. You can always change that with a compiler switch.

>> Another compiler switch to aid transitioning that this DIP 
>> recommends is a -E switch which would function like -I for 
>> imports but would allow the user to specify what the edition 
>> should be for those imports.
>
> Does this override the edition at the module declaration?

I would say no. The purpose of this is for build systems to allow 
setting the default edition package-wide.

Think of a dub package you are using that uses edition 2025, but 
you are on edition 2026. There are no edition specifiers in the 
modules, it's done all through the build system (dub). So when 
you import those modules, you need to specify the default edition 
just for those imports.

-Steve