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Remove uses of the #/ syntax.

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Jim Blandy 1998-10-09 15:13:12 +00:00
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172
libguile/DYNAMIC-LINKING
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@ -1,172 +0,0 @@
Random notes about dynamic linking for Guile. I will update this file
as I go along. Comments are very welcome. I can be reached at
mvo@zagadka.ping.de (Marius Vollmer).
The dynamic linking support is mostly untested. I can't test it
because I don't have all the different platforms, of course. Please
try it out.
To enable support for dynamic linking in libguile, give the
--enable-dynamic-linking
option to configure. It is disabled by default because it will
probably cause lots of problems in its present state. Currently there
is support for -ldld, -ldl, HP-UX (and VMS, but not really).
Files affected:
dynl* new
configure.in add --enable-dynamic-linking option and checking for
system dependencies
Makefile.am include dynl* in build and dist.
init.c initialize dynamic linking support
Here is my plan with indications of progress.
- port "dynl.c" and maybe some parts of "Link.scm" from SCM to
Guile. This should not be difficult, maybe I can even squeeze the
VMS code into the "dynl:link", "dyn:call" interface.
* Mostly done, except VMS, and almost completely untested. The -dl
support should work, but the rest has not even been compiled.
The code is in the "dynl*" files. "dynl.c" is the system independent
portion and includes the appropriate system dependent file, either
"dynl-dld.c", "dynl-dl.c" or "dynl-shl.c".
I have renamed the SCM names of the functions, because they didnn't
fit very well into Guile, the semantics are mostly the same:
SCM name Guile name
dynl:link dynamic-link FILENAME
dynl:call dynamic-call SYMBOL DYNOBJ
dynl:main-call dynamic-args-call SYMBOL DYNOBJ STRING-LIST
dynl:unlink dynamic-unlink DYNOBJ
I plan to generalise dynamic-call and dynamic-args-call to work with
arbitrary arguments, so these names are likely to change.
* There's now one new function
dynamic-func SYMB DYNOBJ
It determines the address of a function in a dynamic object. The
result of this function can be used with `dynamic-call' and
`dynamic-args-call' as the SYMBOL.
PROBLEMS:
Can tsort cope with blank lines? This situation arises when
configure substitutes nothing for @xtra_PLUGIN_guile_libs@.
You may need to link your application in a special way to make
dynamic linking work. For example, on Linux and a statically linked
libguile.a, you need -rdynamic to make the libguile symbols
available for dynamic linking. The solution is probably to build
libguile as a shared library on the systems that support it. Libtool
seems to be the right solution.
* Libguile is now build using libtool and it works fine for me.
- see how to couple dynamic linking with the module system. Dynamic
objects should have a way to specify the module they want to add
their bindings to. Extend this to statically linked parts of
guile. (i.e. posix could be put into a module and initialized on
demand)
* Maybe it will suffice to have scm_make_gsubr, etc to honor the
current scm_top_level_lookup_closure and do all the module switching
from Scheme.
* I now have modified scm_sysintern to use the lookup procedure when
there is one. This is a temporal hack while waiting for the module
system to be accessible from C.
- use gtcltk as a test case for the above, so that TCL/Tk capabilities
can be added to guile at runtime.
* Works.
When you link libgtcltk into your application and initialize it with
scm_init_gtcl ();
scm_init_gtk ();
you get the old behaviour. If you initialize it with
scm_init_ice_9_gtcltk_module ();
the TCL/Tk functions are made available in a module called
#/ice-9/gtcltk.
When you don't link libgtcltk into your application but put it
somewhere in your %load-path, it will be linked dynamically upon the
first `:use-module #/ice-9/gtcltk'. Using the %load-path for this
is probably not very smart.
From boot-9:
;;; Dynamic linking of modules
;; Initializing a module that is written in C is a two step process.
;; First the module's `module init' function is called. This function
;; is expected to call `scm_register_module_xxx' to register the `real
;; init' function. Later, when the module is referenced for the first
;; time, this real init function is called in the right context. See
;; gtcltk-lib/gtcltk-module.c for an example.
;;
;; The code for the module can be in a regular shared library (so that
;; the `module init' function will be called when libguile is
;; initialized). Or it can be dynamically linked.
;;
;; You can safely call `scm_register_module_xxx' before libguile
;; itself is initialized. You could call it from an C++ constructor
;; of a static object, for example.
;;
;; To make your Guile extension into a dynamic linkable module, follow
;; these easy steps:
;;
;; - Find a name for your module, like #/ice-9/gtcltk
;; - Write a function with a name like
;;
;; scm_init_ice_9_gtcltk_module
;;
;; This is your `module init' function. It should call
;;
;; scm_register_module_xxx ("ice-9 gtcltk", scm_init_gtcltk);
;;
;; "ice-9 gtcltk" is the C version of the module name. Slashes are
;; replaced by spaces, the rest is untouched. `scm_init_gtcltk' is
;; the real init function that executes the usual initilizations
;; like making new smobs, etc.
;;
;; - Make a shared library with your code and a name like
;;
;; ice-9/libgtcltk.so
;;
;; and put it somewhere in %load-path.
;;
;; - Then you can simply write `:use-module #/ice-9/gtcltk' and it
;; will be linked automatically.
;;
;; This is all very experimental.
- see how G-Wrap and libffi can work together and extend dyn:call to
functions taking arbitrary arguments. Something along the lines
(define XOpenDisplay (make-foreign-function X11-lib 'XOpenDisplay
.. whatever args ..))
* I have received Guile libffi glue code from Anthony Green but I have
yet to try it out.
* There is now some code at
http//www-nt.e-technik.uni-dortmund.de/m_mvo/guile-ffi-970501.tar.gz
but it doesn't address G-Wrap.