Comment (by Roland Haas):

Ideally the library would become an ExternalLibrary (same as say LORENE https://github.com/einsteinToolkit/externalLibraries-lorene) and the reader thorn would REQUIRE it (like Meudon_Bin_NS https://bitbucket.org/einsteintoolkit/einsteininitialdata/src/master/Meudon_Bin_NS/ in file configuration.ccl).

This has the advantage that multiple different ID readers can use the same ExternalLibrarry eg for BBH or BNS or BHNS initial data. Those should not be all handled by a single thorn since eg the BNS or BHNS reader will need to provide data in thorn HydroBase which would not be active for a pure vacuum run.

If the library cannot be incorporated as an ExternalLibrary (eg b/c it requires use of C++ features not allowed in C++11 or Fortran newer than Fortran 2008) then you could have the ID thorns take FOO_DIR etc option list variables the way an ExternalLibrary thorn would do. However this would mean that a user who would like to compile in multiple different ID thorns all using Elliptica’s library would have to, potentially, set multiple option list variables with identical values.

On the technical level, you can tell the build system which library to link against and the path to find is using configuration.ccl by adding a (http://einsteintoolkit.org/usersguide/UsersGuide.html#x1-53000C1.2.3) block

PROVIDES <My_Capability>
{
  SCRIPT <My_ConfigScript>
  LANG <My_Language>
}

where My_ConfigScript has to produce output that adheres to the syntax d

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2619/include-ellipitca-reader-in-einstein