[racket-dev] planet2 and versions

On 12/12/2012 03:13 PM, Carl Eastlund wrote:
> I believe it is by design that Planet 2 does not resolve this kind of
> issue.  This gives us room to experiment with different solutions
> without committing to one up-front, since Planet 1 ran into various
> limitations of its built-in policies.
>
> I will propose one possible solution for your "webapis" example.
> Distribute a primary wrapper package called "webapis" and separate
> specific versions such as "webapis1", "webapis2", and so forth.  Have
> the code in "webapis" determine at compile-time which specific version
> of webapis is appropriate for the current Racket version and install
> that package.  The specific packages would contain the actual code a
> client would import.  That way, installing the "webapis" package on any
> Racket version would install only the version of the implementation that
> works.

IIUC, a package's dependencies are fixed at package creation time; they 
can't be adjusted at compile time. (Well, now that the dependencies are 
specified via an expression in a #lang setup/infotab file, maybe it's 
possible to adjust them at compile time... or maybe installation time? 
But there's still no access to the Racket version, although there's 
access to other things....)

Ryan


> I don't know if this is a complete solution, but it seems like a
> reasonable starting point.  As we figure out what patterns work, they
> themselves can be developed as reusable tools and built into their own
> packages.  I think this room for improvement will make Planet 2 a much
> better long-term model than Planet 1.  Of course we do eventually want a
> default system that package developers can use without too much mucking
> about with "experimental" versioning systems.  But I think an initial
> period of "crowd-sourcing" the design of that system will do us some good.
>
> Carl Eastlund
>
>
>
> On Wed, Dec 12, 2012 at 2:29 PM, Ryan Culpepper <ryan at cs.utah.edu
> <mailto:ryan at cs.utah.edu>> wrote:
>
>     I'm trying to understand how things are supposed to work in planet2
>     without version information.
>
>     Let's say I release a package, "webapis". Time passes, and I notice
>     that Racket gets some cool new features (eg, better SSL support)
>     that the "webapis" package should use. I write the code, and ...
>
>     Do I release the new code under the same package name? If so, then
>     the package breaks for older versions of Racket, because IIUC
>     planet2 has nothing corresponding to planet1's
>     'required-core-version field. And there doesn't seem to be a way to
>     tell Racket "no, sorry, go back to the older version of the
>     package". (Rather, there's no way for a client to do so. The fix
>     would be for the package maintainer to release an "upgrade" that
>     reverts to the old code.) So it seems like it would be really bad
>     for me to release the new code under the name "webapis".
>
>     In other words, if a package changes its dependencies, that's an
>     incompatible change for the package, and it needs a new name. Right?
>
>     Suppose I release the new code as "webapis2". And suppose there's
>     another package (let's call it "scriblogify") that depends on
>     "webapis". If that code wants to use "webapis2", that's a dependency
>     change, so it would have to be released as "scriblogify2". There's
>     no way to express "link me with the most recent compatible version
>     of webapis*", right?
>
>     Ryan
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