On 03/03/2015 15:55, Gerd Stolpmann wrote:

Am Dienstag, den 03.03.2015, 14:15 +0100 schrieb François Bobot:

Gerd, do you think that something that does that could be added to ocamlfind? One tricky thing is to
know the library statically linked (ie. `Ocsigen_config.builtin_packages`), perhaps ocamlfind can
during linking add this information.

I think so. For toploops, there is already code that tracks libraries
already linked into the executable (i.e. if you ocamlmktop your
toploop).

All was already in place indeed! It was easy to add. I kept caml-list in CC for discussing the big picture in order to get comments from people. Is mail still your preferred way of receiving patch?

I kept it simple, no hack (no automatic: cmxa -> cmxs) because I prefer problems in library META to be found than to be paper over.

The first patch adds:
- A library `findlib.dynlink` that depends on `findlib` and `dynlink`
- During linking (using `ocamlfind ocaml*`) if `-package findlib.dynlink` and `-linkpkg` are used then a module `Findlib_initl...` is linked after all packages and it stores the names of packages linked in `Findlib.linked_packages`.
- In the main program `Fl_dynlink.load_packages ["yojson"]` can be used to dynlink packages

The second patch forbids to run `Fl_dynlink.load_packages` during the initialization of packages (statically or dynamically linked), because `Findlib_initl...` is not yet run and because if you want to load a package that depend on a statically linked package not yet initialized, there is no sane semantic.

Problems:
- The package is named `findlib.dynlink`, the archive `findlib_dynlink.cm*` and the module `Fl_dynlink` ...
- If you don't use `-linkall` static packages could only be partially linked, and you can't link the remaining part later. So perhaps `-linkall` must be automatically added if `findlib.dynlink` is used.
- If you define `archive(native)` and not `archive(native,plugin)` the error is not nice (in Dynlink.Error). Perhaps I should add a `Package_not_dynamically_loadable of string` error, that should catch the loading of something else than `*.cmxs`.
- Often you link your binary with your own library without using `-package` (the library is not yet installed), and plugins for your tools depend on your library. Currently you should do before any `Fl_dynlink.load_packages`: `Findlib.linked_packages := "mylib"::Findlib.linked_packages`. For simplicity, I don't know if I should add a function `Fl_dynlink.add_linked_packages`, or an option to ocamlfind `-additional-package-statically-linked `.
- During the initialization of your own library (linked without -package) you should not use `Fl_dynlink.load_packages`, but the library doesn't protect you against this error.

Choices:
- If you don't link with `findlib.dynlink` or use `create_toploop`, the variables `Findlib.linked_packages` and `Findlib.linked_predicates` are empty because I don't wanted to add backward change by adding `Findlib_initl...` when `findlib` is linked.


Remains to do:
- Fix problems
- Documentations (add `plugin` in the list of standard predicates, ...)


Gerg, what do you think of this first version of the patch? Of the way to fix the problems?

Thanks,

Regards,

--
François

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