Re: installation with opam install files

[Hendrik Tews <hendrik@askra.de>]

>> install-script: add an install script to the new topkg package,
>
> This could work for packages that ship a static install file. But what
> happens for packages that generate their install file during the build?

The script needs to be sufficiently complex to deal with all
possible configurations. Which is what ordinary makefiles do in
there install target.

The downside of the install-script approach is that we would need
to maintain such scripts for all packages in the transitive
build-depends closure of opam that use topkg, for instance also
for cmdliner.

>> perl-installer: write a replacement for opam-installer, for
>>         instance in perl.
>
> This is my preference.

Also my preference now. I am discussing this build dependency
cycle off-list also with Daniel Bünzli. There I learned that
there is already an OCaml library that can read these .install
files: opam-file-format. The perl-installer will therefore
probably be written in OCaml.

I am also discussing with Daniel the chance that upstream solves
the problem for us by changing opam-installer such that it does
not depend on all the build-dependencies of opam. The outcome
here is not clear yet, but assuming upstream decides to go this
way, how long are we willing to wait? Or, the other way round,
how long can we wait before updating cmdliner and all the other
packages that now depend on topkg? I guess waiting for 2-3 month
would be fine, but if the delay would be longer, we should pursue
our own solution?

Hendrik