[Oberon] Modula2 vs Oberon IMPORT

Duke Normandin dukeofperl at ml1.net
Sat Jan 8 20:45:05 CET 2011

On Sat, 8 Jan 2011, Christian Demmer wrote:

> Duke Normandin wrote:
> >IMHO, "clever" compilers that IMPORT _only_ the required code, is the
> >ideal situation.
> I think there is a misunderstanding of import of symbols and code and
> separate compilation in general here.
> If a module is compiled the compiler writes a symbol file which contains
> information (names etc.) about the module and all exported symbols and a
> object file which contains the code for this module. There is no code in
> a symbol file.
> If a second module is compiled which imports the first
> module, the compiler reads the symbol file of the first module. The
> object file, which contains the code of the second module has only
> references to code and variables in the first module which must be
> resolved by a linker. That could be a static linker or a loadtime
> linker like the one in the original Oberon system.
> How this is done depends on the system used.
> >Yes! I realized that about qualified IMPORTs - after all, the entire
> >Module is referenced in the IMPORT statement. Qualified imports simply
> >allow you to use procedures with the same name, as I understand it.
> Qualified import is more or less a syntax feature and most likely not
> related to the implementation of the code generator.
> >My concern is this - if a "main" Module IMPORTS 10 "slave" Modules,
> >but uses only (e.g.) one procedure from each, then the code bloat in
> >the final executable would be absurd, would it not? I might as well
> >cut-n-paste the code into the "main" module, and re-use the code that
> >way. Maybe this something a "peephole optimizer" could do?
> As explained above no such thing will happen. The compiler moves symbols
> around. No code, only references to external code are handled by the
> compiler.
> Hope this helps,

I'm not yet sure! Are you referring to the way things are on an Oberon
OS system, or otherwise? I'm learning Oberon-2 (and the Pascal-family)
on a Linux box. Do your comments apply on such as system as well?

More information about the Oberon mailing list