NetNews Usenet Archive 1992 #20/NN_1992_20.iso/spool/comp/unix/programm/4607

Text File | 1992-09-10 | 1.8 KB | 39 lines

Newsgroups: comp.unix.programmer
Path: sparky!uunet!spool.mu.edu!yale.edu!ira.uka.de!math.fu-berlin.de!zrz.tu-berlin.de!cs.tu-berlin.de!net
From: [e-mail] (Oliver Laumann)
Subject: Re: Dynamic linking
Message-ID: <[e-mail]>
Sender: [e-mail]
Organization: Technical University of Berlin, Germany
References: <[e-mail]> <[e-mail]> <[e-mail]>
Date: Thu, 10 Sep 1992 11:38:49 GMT
Lines: 27

In article <[e-mail]> [e-mail] (Guy Harris) writes:
> >However, it only runs under BSD flavours of UNIX at the moment, as
> >I recall; I don't think it is likely to support ELF or other library
> >formats in the foreseeable future (according to Wilson).
>
> For most, if not all, purposes, you don't need a port of any third-party
> dynamic linking code to ELF; any system that I'd consider worthy of the
> name "System V Release 4" has the "-ldl" library.  (Yes, there are
> probably things you can't do with it [...]

The important point here is that there are things you can't do with
-ldl which you *can* do with the DLD package and with BSD-style dynamic
loading in general (on which DLD is based).

For example, an object file dynamically loaded by means of DLD can
directly reference symbols defined by other object files that have
been loaded earlier, while shared objects attached to a program through
the dl-library's dlopen() function can *not* directly reference symbols
exported by objects that have been opened by earlier calls to dlopen().

This functionality is important (and is required by programs like Lisp
and Scheme interpreters), which is the reason why a port of the DLD
package to ELF-based systems would be quite useful (but certainly
diffcult).

--
Oliver Laumann    [e-mail]  [e-mail]  [e-mail]