Longstanding issues: structs & standalone Erlang

[Vlad Dumitrescu XX (LN/EAB)]

> -----Original Message-----
> [mailto:owner-erlang-questions@REDACTED] On Behalf Of Romain Lenglet

> I completely agree. Packaging concerns must  be left OUT of the Erlang
implementation.
> [...]
> And to install only parts of Erlang/OTP according to the 
> needs of specific apps, the solution on Debian is quite 
> straightforward: 
> we should split the "erlang" and "erlang-base" packages into 
> one package for every app, with the right dependencies 
> between those packages.
> E.g. the "os_mon-erlang" Debian package would have the following
> dependencies:
> Depends: kernel-erlang (>= 2.10), stdlib-erlang (>= 1.13)
> Recommends: sasl-erlang (>= 2.0)

Could you please explain how is this to work in practice without somehow
making the runtime aware of this mechanism? I don't get it.

Suppose I have an app A1 that requires stdlib >= 4.13, and an app A2
that requires stdlib <= 4.12. Both of those can run with kernel >= 4.3

Now if A1 and A2 are standalone applications, it will work, because they
will have separate startup scripts that will reference the correct
stdlib in the code path.

But if I start my Erlang node (that references stdlib 4.15) just to try
things up, how would I make sure only A1 and not A2 is available, unless
the runtime is aware of these dependency declarations?

Regards,
Vlad