Runtime package dependencies and compilation order

[Boris]

Hello,

Recently I've faced following problem. I have a package A that might depend
on package B or (disjunction) package C. But dependency list is not known
upwards, because the list itself depends on user settings. So I don't
specify B and C in package requires section of package A. All packages are
on MELPA and installed via package.el. The problem comes when someone wants
to use the part of package A that depends on package B - if package A is
byte compiled before B, then some functionality doesn't work and you have
to manually recompile A. So the solution might be pretty simple - ask user
to install package A after package B. But in some setups there is no way (I
mean, good way) of enforcing specific order of installation. And in any
case I feel like asking such thing from users is not the right thing.

>From my understanding specifying package B as dependency solves such
issues, as package manager installs B before A. So the only solution I see
in such situation is to create package A-base, A-B (B-related functionality
that has two packages as dependency - A-base and B) and A-C (similar to
A-B).

So I would like to ask if there's any other solution for the described
problem?

I hope that this is the right place to ask such questions, and sorry for
such an abstract description.

Best regards,
Boris
-- 
Best regards,
Boris @ d12frosted