Re: Compiling emacs-24.0.90 on AIX 5.3

["Stephen J. Turnbull" <stephen@xemacs.org>]

Glenn Morris writes:

 > However, you may be disappointed because I cannot think of any new
 > feature that fits this description. Do you mean Lisp code or literal
 > libfoo.so libraries?

I suppose he means DLLs that wrap libraries such as zlib or libpng,
which have until recently been prohibited because they may allow an
inadvertant run-around the GPL, and now are under consideration
because a reasonable way to ensure that users who want only GPL
plugins will get them has been developed.  This would allow writing a
version of `load' that loads such features on demand (eg, via
`(require 'dbus)' or similar).  ISTR that the related FFI feature may
also now be OK.

Because the wrapper DLLs are demand-loaded, they could be built on a
"loaded" system with all necessary libraries, and distributed with
Emacs (eg, on a corporate network).  On a "lightweight" system with
few system libraries, Emacs would run, but attempts to use those
features would fail at the `require' stage.  There would be no need to
recompile Emacs to take advantage of newly added system libraries.
(In theory; in practice many free software libraries have enough "API
churn" that even with DLLs you need to rebuild the wrapper DLLs when
new versions come out.)

I don't think there's any "official" development roadmap to these
features yet, just Richard's statement that the GPL marking method
used by GCC has been vetted by the FSF's lawyers and should be good
enough for Emacs, too.  AFAIK no decision has been made about whether
either on-demand DLL loading or FFI is technically suited for Emacs.