Preventing access to internal library subroutines

[OP1]

I apologize if this question has already been asked and answered before... I would like to know how to prevent future users of my libraries to call someinternal subroutines in these libraries.

For instance, assume that I have two subroutines S_PUBLIC and S_PRIVATE in a library. S_PUBLIC is meant for usage by customer's codes; S_PRIVATE is a utility subroutine that is used by S_PUBLIC but which should not be accessed outside the library.

How would I enforce this?

Thank you!

Olivier

[TimP]

I suppose you would put the private subroutine in a module and declare it private.

[OP1]

Quoting - tim18

I suppose you would put the private subroutine in a module and declare it private.

Thanks Tim... yes, this solution would work if you only have a limited number of small subroutines. But this is not convenient when you have a lot of large subroutines... the resulting module would be unwieldy for later maintenance, upgrades etc...

Is there another solution?

For instance, I am sure that the MKL libraries refer to many internal subroutines that one cannot access when these libraries are linked in a program. How is it done?

Olivier

[anthonyrichards]

Make it a dynamic link library and only export the public symbols?

[OP1]

Quoting - anthonyrichards

Make it a dynamic link library and only export the public symbols?

Yes, but what about static libraries? There is no equivalent facility provided for static libraries?

[Steven_L_Intel1 · Accepted solution]

There is no way to prevent someone from calling a routine in a static library. Typically what one would do is choose a naming convention that separates the private routines from the public ones.

Of course, of you provide your procedures in modules, you can use Fortran's accessibility attributes (PUBLIC/PRIVATE) to specify that everything is private unless made public. This affects users of the module - theoretically, if someone figured out the private routine name and wrote their own interface (without using the module), they could call it.