Thoughts about D package management on Gentoo

[Dicebot]

Some comments on general packaging topic.

On Saturday, 9 November 2013 at 00:38:16 UTC, Marco Leise wrote:
> - Compiler and library are closely coupled and depend on each
>   other.

Not really true, it is straightforward to write an alternative 
druntime / stdlib substitution to use with existing compiler 
package.

> - Each new D point release brings a new, generally
>   incompatible standard library.
> - All three major compiler backends are in good shape and use.
>   But their generated code is not exchangeable (as far as
>   I've heard due to ABI differences).

Yes, ABI is the key issue that makes 3 major compiler ecosystems 
not interchangeable in any way. And it is not likely to be fixed 
any time soon.

> - Tools tend to expect that "dmd" is available as a command.

Actually I don't think this is true for newer ones. There are 
plenty that tend to either use `rdmd` or detect compiler present 
in the system.

> To deal with the complexity of package dependency management
> in this scenario, we need to be able to install multiple
> versions of D compilers in parallel (similar to what dvm does).
> This can be accomplished by so called "slots" for each point
> release. We can do this for all three compilers and will end
> up with binaries like "dmd2.064" and "gdc2.063".

I have been thinking about it when doing Arch packaging but 
discarded that approach as not KISS. All maintained applications 
support either latest compiler version or previous one. Rare 
cases when legacy version is needed are covered by dvm. In that 
sense pure bleeding edge model suits D realities most and only 
separation between dmd/ldc/gdc is needed.

> Next a symlink should be established to the current
> implementation of dmd, e.g.: /bin/dmd -> /bin/ldmd2.
> This symlink could be managed with an eselect plugin as it is
> already done for other languages like Python or the Java
> Runtime.

And what if one wants to have all 3 simultaneously?

> ...

(rest is a bit too Gentoo-specific for me to make any reasonable 
input :))