On Dec 21, 2012 2:25 AM, "Bohuslav Kabrda" <bkabrda@redhat.com> wrote
>> This sounds like a productive piece of discussion.  So is sounds like you desire to create as few packages as possible to create a full stack for c-ruby, jruby, and other implementations of the ruby language.
>> What rpm dependencies are used for are to guarantee that when a user installs a package, the things that package needs to run are also installed.
>> ( Note: If I use "when" below, i'm asking what conventions exist to map those types of changes to bumps in the version number of upstream releases.)
>> It's when we put these two things together that things start to get tricky.  When does the ruby language itself change? (For instance, if blocks were only specified with curly braces in one version but could be specified with either curly braces or parentheses in a later version.) (Another for instance, if a new keyword is added to the language).
> The standard for Ruby language is the cRuby. E.g. Matz decides what appears and what does not appear in next versions. Tiny versions keep the ABI and API mostly the same (e.g. 1.8.3 can run anything that 1.8.2 could, but 1.8.3 may have some minor feauture enahancements, AFAIK),  whereas minor and major versions may change both ABI and API (for example 1.8.x to 1.9.x or 1.9.x to 2.x.x).

After reading your whole post the first thing I need to make sure of is that when you talk about abi and api here you are talking about the c library correct?  You are not talking about the other things that the python(abi) virtual provide covers or the things that the ruby(abi) as currently written is intended to cover?

Second, when you talk about minor feature enhancements, that includes the things that I mentioned? (Changes to the ruby language, api additions, deletions, and changes to the ruby stdlib, changes to the filesystem layout that have visibility to other ruby packages or ruby users).  Is it policy that those types of changes are allowed or do they just slip in once in a while because no one realized that a particular change would have that sort of effect?

Well, when I say "abi", I mean the C library, but when I say "api", I mean the pure Ruby language, which can be interpreted by any Ruby interpreter. I think we need to distinguish these two - ruby(api) for pure Ruby libraries and ruby(abi) or jruby(???) for those that contain an extension.
As for the second point, AFAIK they "slip once in a while".

>> Is the ruby stdlib shipped separately from the interpreter to users?  Are types part of the stdlib or the interpreter?  When can those be added or changed?  These are examples of the types of incompatibilities that we use python(abi) for (rather than a true c-library usage of the term).
> Ruby stdlib is shipped with the interpreter, types are part of the interpreter - they can be changed as explained above.

Thanks further thoughts/questions as a result of this included above.

>> You say that jruby doesn't provide an abi. Are you meaning for extensions or the types of changes mentioned above?  Does jruby target certain revisions of the above that certain versions of cruby have implemented at a certain version or is it a mixture of some features from one release and some features from a different revision?
> I mean "abi" as in "libruby.so.x.x", so for extensions.

Okay.  That's not how fedora traditionally used these virtual provides as that would be redundant with the requires on the shared library.  The virtual provides were used on the things that I mentioned instead (it sounds like those things might be called "compat modes" by ruby people.  Is that correct?)

Yep, I think so.

> JRuby always supports certain version(s) - compat modes - of Ruby. Right now, it supports 1.9 and 1.8 (and new features from next version of cRuby continuously land in the latest compat mode, so e.g. the 1.9 compat mode of JRuby may be in fact a bit different from cRuby 1.9).

This sounds like a version of a compat mode isn't finalized until the last cruby release of that version is released?

What do you mean when saying "finalized"? If you mean that e.g. features from 1.8.x to 1.8.y land continuously in the JRuby's 1.8 compat mode, then the answer to your question is yes.

Does compat mode cover both the stdlib and the language or just the language?


How long does jruby lag behind cruby in terms of implementing these features?

Now that's a tricky question :) It depends on the feature complexity, I guess, but AFAIK the JRuby upstream is trying to keep as close as possible and doesn't delay anything on purpose.

Is compat mode canonized in the cruby and jruby code or is it just a convenient concept?

More of a convenient concept, to my knowledge.

>> Depending on where we can get compatibility, it may make sense to have one virtual provide or one for the interpreter and one for the stdlib or one for the interpreter and several for the stdlib.  We might also end up deciding to implement something similar to Debian/Ubuntu's python-commons setup for ruby or deciding that building a full stack from one version of the packageset is too hard to validate so having separate packages is better in the long run.
> As mentioned, I would prefer having something like "ruby(interpreter)" provided by both cRuby and JRuby. This would be required by all Ruby packages.

Does that also cover changes to the ruby stdlib, filesystem layout, etc?  If so, it should simply be a rename of ruby(abi) for cruby and packages that depend on it.  Adding jruby to the mix, i'm not yet certain of how much compatibility there is here.  I'm also not sure how much incompatibility we're willing to push onto users.

Packages with implementation specific extension would then require "ruby(abi)" or "jruby(?)" (maybe just jruby).
If I understand what you're saying here, there's no point to ruby(abi) in those circumstances.  Extensions would depend on certain versions of the shared library (which is what you seem to have thought ruby(abi) represented) and they probably also need to depend on ruby(interpreter) or whatever virtual provide we use for the combination of language features, stdlib apis, filesystem layout, and other things that determine if a package will install and run with an installed interpreter.

Yes, exactly. If we say that ruby(abi) is for depending on a certain version of shared library, we don't need it, because RPM will take care of that. The only reason that would  make sense for ruby(abi) to exist is, that JRuby extension packages will have Requires: jruby, so it may be nice to have a cRuby counterpart of that, just for convenience. And yes, ruby(interpreter) or ruby(compat) (have a better name?) is what all the ruby packages (both pure and with extensions) should contain.


Bohuslav "Slavek" Kabrda.