Re: [gentoo-dev] RFC about another *DEPEND variable

[Duncan Coutts]

On Thu, 2006-09-21 at 11:11 -0400, Mike Frysinger wrote:
> On Thursday 21 September 2006 10:56, Duncan Coutts wrote:
> > If we do go in this direction it'd be great to be able to slot on the
> > ABI and still have dependencies resolved correctly. For example imagine
> > having parallel python-2.3 and 2.4 installations with some libs
> > installed for both. Crucially, deps need to be resolved to the version
> > of a lib with the right ABI.
>
> ugh, no ... we are not a binary distribution so we should not have to worry
> about ABI baggage

So we can't ever install two versions of python or ghc at once? That
seems a shame.

> we SLOT based upon API, not ABI

Here's another example; I'm not sure if it passes the ABI/API test:

We would like to support 3 Haskell implementations:
  * GHC which compiles to native code (ELF binaries & static .a libs)
  * Hugs which is an interpreter so installation is .hs source files
  * YHC which compiles to portable bytecode

A single Haskell library is likely to work with all three
implementations. So that's API.

Once installed however each implementation is very different. So that's
incompatible ABI.

This could be 'solved' by having dev-haskell/foo-ghc,
dev-haskell/foo-hugs, dev-haskell/foo-yhc, but that's obviously not the
Gentoo way (though it's pretty much what debian does).

These multiple impls is pretty similar to multiple versions of the same
compiler.

So my point is, I don't think it can be simply dismissed as ABI nonsense
that we don't have to deal with. Being able to SLOT on the compiler
flavour (and possibly version) would allow us to do useful things that
we cannot currently do.

Duncan

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