Doc improvements, pre-inst-env wrapper, optional devtype

.gitignore

@@ -8,4 +8,5 @@ config.log
 config.status
 configure
 libtool
+pre-inst-env
 TAGS

AUTHORS

@@ -7,4 +7,6 @@ See also files THANKS and ChangeLog.
 * Antlers <[email protected]>
   Bug fixes in 'libguile-udev/udev-monitor-func.c'
 * Mathieu Othacehe <[email protected]>
-  Bug reports in GNU Guix mailing list.
+  Bug reports in GNU Guix mailing list.
+* Maxim Cournoyer <[email protected]>
+  Improvements to the documentation.

build-aux/compile

@@ -1,4 +1,4 @@
-#! /bin/sh
+#!/bin/sh
 # Wrapper for compilers which do not understand '-c -o'.
 
 scriptversion=2018-03-07.03; # UTC

configure.ac

@@ -109,6 +109,7 @@ AC_SUBST([guilesitedir])
 GUILE_EFFECTIVE_VERSION=`$GUILE -c '(display (effective-version))'`
 AC_SUBST(GUILE_EFFECTIVE_VERSION)
 
+AC_CONFIG_FILES([pre-inst-env], [chmod +x pre-inst-env])
 AC_CONFIG_FILES([Makefile libguile-udev/Makefile build-aux/Makefile])
 AC_CONFIG_FILES([build-aux/m4/Makefile build-aux/am/Makefile doc/Makefile])
 AC_CONFIG_FILES([modules/Makefile modules/udev/Makefile])

doc/guile-udev.texi

@@ -11,6 +11,7 @@
 This manual documents Guile-Udev version @value{VERSION}.
 
 Copyright (C) 2020 Artyom V. Poptsov @email{poptsov.artyom@@gmail.com}
+Copyright (C) 2023 Maxim Cournoyer @email{maxim.cournoyer@@gmail.com}
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.3 or
@@ -54,11 +55,11 @@ Documentation License.''
 
 @menu
 * Introduction::
-* Installation::
-* API Reference::
-
-Appendices
-
+* Installing as a system package::
+* Installing from sources::
+* Using this library before it is installed::
+* API Reference::               Appendices
+* Examples::
 * GNU Free Documentation License::  The license of this manual.
 
 @end menu
@@ -72,8 +73,19 @@ Guile-Udev is a module that provides bindings to
 @url{https://www.freedesktop.org/software/systemd/man/libudev.html, libudev}
 for programs written in @url{https://www.gnu.org/software/guile/, GNU Guile}.
 
-@node Installation
-@chapter Installation
+@node Installing as a system package
+@chapter Installing as a system package
+
+The @url{https://guix.gnu.org, GNU Guix} package manager, which can run on top
+of any GNU(/Linux) distribution, offers a @code{guile-udev} package which can
+be installed via:
+
+@example
+guix install guile-udev
+@end example
+
+@node Installing from sources
+@chapter Installing from sources
 
 Guile-Udev sources are available from GitHub at
 @url{https://github.com/artyom-poptsov/guile-udev/}. This section describes
@@ -86,6 +98,15 @@ Guile-Udev depends on the following packages:
 @item libudev
 @end itemize
 
+Alternatively, if you have GNU Guix installed, you can run:
+
+@example
+guix shell
+@end example
+
+After following the instructions displayed by the above command to authorize
+automatically loading the @file{guix.scm} file at the root of the repository.
+
 Get the sources of Guile-Udev from GitHub using Git (a good introduction to Git
 is @url{https://git-scm.com/book/en/v2, Pro Git} book, which is available
 online):
@@ -118,6 +139,17 @@ installed in Guile's default path.  But, if you don't know where your
 Guile site directory is, run @command{configure} without the option,
 and it will give you a suggestion.
 
+@node Using this library before it is installed
+@chapter Using this library before it is installed
+
+If you would like to test this Guile extension as you work on it, without
+having to install it, you can use the @file{pre-inst-env} wrapper after having
+configured and built the project, e.g.@:
+
+@example
+./pre-inst-env examples/device-listener.scm
+@end example
+
 @node API Reference
 @chapter API Reference
 
@@ -155,16 +187,20 @@ parameters specified by keywords described below.
 
 @table @samp
 @item callback
-Callback to be called when an udev event occurs.
+A procedure to be called when an udev event occurs.  It gets applied to a
+single argument, which is the @code{udev-device} object the event originated
+from.
 
 Expected type: procedure
 
 Default value: @code{(const #f)}
 @item filter
 Udev event filter.
 
-Expected type: a list with two elements: the 1st element is sybsystem name,
-the 2nd element is device type
+Expected type: a list with two elements: the first element is the subsystem
+name, while the second element is the device type.  To match @emph{any} device
+type, you may use @code{#f} instead of an actual device type.  If needed, more
+filters can be installed via the @code{udev-monitor-add-filter!} procedure.
 
 Default value: @code{#f}
 
@@ -205,9 +241,12 @@ Check if @var{x} is an udev-monitor object. Return @code{#t} if it is, or
 @code{#f} otherwise.
 @end deffn
 
-@deffn {Scheme Procedure} udev-monitor-add-filter! udev-monitor sybsystem devtype
+@deffn {Scheme Procedure} udev-monitor-add-filter! udev-monitor subsystem [devtype]
 Add a new filter for the events on @var{udev-monitor} that will trigger the
-provided callback. This procedure must be called before starting the scanning.
+provided callback, for a device of type @var{devtype} belonging to the
+@var{subsystem} subsystem.  @var{devtype} is optional; when omitted, devices
+of @emph{any} type are matched.  This procedure must be called before starting
+the scanning.
 @end deffn
 
 @deffn {Scheme Procedure} udev-monitor-remove-filters! udev-monitor
@@ -328,6 +367,27 @@ Usage example:
 
 @end deffn
 
+@node Examples
+@chapter Examples
+
+Here's an example of a device listener that prints the device path of USB
+devices that emit udev events:
+
+@lisp
+@verbatiminclude ../examples/device-listener.scm
+@end lisp
+
+To trigger USB events without actually inserting or removing USB devices into
+your computer, you can use the @command{udevadm} command (provided by the
+@code{eudev} package from Guix) @emph{as root}:
+
+@example
+# udevadm trigger --verbose --subsystem-match=usb
+@end example
+
+You can find the source of this example in the @file{examples} directory of
+the project.
+
 @node GNU Free Documentation License
 @appendix GNU Free Documentation License
 

examples/device-listener.scm

@@ -1,5 +1,4 @@
-#!/usr/bin/guile \
--L modules -e main -s
+#!/usr/bin/env -S guile -L modules -e main -s
 !#
 
 (use-modules (udev udev)

libguile-udev/udev-monitor-func.c

@@ -30,9 +30,11 @@
 #include "udev-device-type.h"
 #include "error.h"
 
-SCM_DEFINE_N(gudev_add_filter_x, "udev-monitor-add-filter!", 3,
-             (SCM udev_monitor, SCM subsystem, SCM devtype),
-             "Add a filter to the monitor.")
+SCM_DEFINE(gudev_add_filter_x, "udev-monitor-add-filter!", 2, 1, 0,
+           (SCM udev_monitor, SCM subsystem, SCM devtype),
+           "Add a filter to the monitor.  @var{subsystem} is the subsystem\n"
+	   "associated with a device while @var{devtype} is its device type.\n"
+	   "The @var{devtype} argument is optional.")
 #define FUNC_NAME s_gudev_add_filter_x
 {
     char* c_subsystem = NULL;
@@ -41,14 +43,17 @@ SCM_DEFINE_N(gudev_add_filter_x, "udev-monitor-add-filter!", 3,
     int result;
 
     SCM_ASSERT(scm_is_string(subsystem), subsystem, SCM_ARG1, FUNC_NAME);
-    SCM_ASSERT(scm_is_string(devtype),   devtype,   SCM_ARG2, FUNC_NAME);
+    SCM_ASSERT(scm_is_string(devtype) || SCM_UNBNDP(devtype), devtype,
+	       SCM_ARG2, FUNC_NAME);
 
     scm_dynwind_begin(0);
 
     c_subsystem = scm_to_locale_string(subsystem);
     scm_dynwind_free(c_subsystem);
 
-    c_devtype   = scm_to_locale_string(devtype);
+    if (!SCM_UNBNDP(devtype))
+        c_devtype = scm_to_locale_string(devtype);
+
     scm_dynwind_free(c_devtype);
 
     result = udev_monitor_filter_add_match_subsystem_devtype(umd->udev_monitor,

modules/udev/monitor.scm

@@ -24,12 +24,21 @@
                             (filter       #f)
                             (timeout-usec 0)
                             (timeout-sec  0))
+  "Create a new 'udev-monitor' object configured with the specified parameters.
+CALLBACK is a one argument procedure (receiving a 'udev-device' object) called
+when an event matching the specified FILTER.  FILTER is a list whose first
+element is the device subsystem, and whose second argument is the device type,
+or #f to match any type."
   (let ((monitor (%make-udev-monitor udev)))
     (udev-monitor-set-timeout!  monitor timeout-sec timeout-usec)
     (udev-monitor-set-callback! monitor callback)
     (udev-monitor-set-error-callback! monitor callback)
     (when filter
-      (udev-monitor-add-filter! monitor (car filter) (cadr filter)))
+      (let ((subsystem (car filter))
+            (devtype (cadr filter)))
+        (if devtype
+            (udev-monitor-add-filter! monitor subsystem devtype)
+            (udev-monitor-add-filter! monitor subsystem))))
     monitor))
 
 (load-extension "libguile-udev" "init_udev_monitor")

pre-inst-env.in

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+abs_top_srcdir="`cd "@abs_top_srcdir@" > /dev/null; pwd`"
+abs_top_builddir="`cd "@abs_top_builddir@" > /dev/null; pwd`"
+
+GUILE_EXTENSIONS_PATH="$abs_top_builddir/libguile-udev/.libs${GUILE_EXTENSIONS_PATH=:+:}$GUILE_EXTENSIONS_PATH"
+GUILE_LOAD_COMPILED_PATH="$abs_top_builddir/modules${GUILE_LOAD_COMPILED_PATH:+:}$GUILE_LOAD_COMPILED_PATH"
+GUILE_LOAD_PATH="$abs_top_srcdir/modules${GUILE_LOAD_PATH:+:}:$GUILE_LOAD_PATH"
+export GUILE_EXTENSIONS_PATH GUILE_LOAD_COMPILED_PATH GUILE_LOAD_PATH
+
+PATH="$abs_top_builddir/scripts:$PATH"
+export PATH
+
+exec "$@"