configure.ac: Expand rules for setting package/library version.

The comedilib manual version is usually only updated if the manual has
changed since the previous release (although it ought to change anyway
if any library interfaces have changed).  Allow a lower-case letter (or
sequence of letters) to be appended to the comedilib package version if
the only changes are outside the library sources and language bindings.

diff --git a/configure.ac b/configure.ac
index 1b4bf41d9d4961a6b8194c9fee0f5a6b9be87f31..4e22f4d967fa6ab304e0a8c960f043a25a5ad86c 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -21,24 +21,40 @@
 m4_define([comedilib_lt_current], [10])
 m4_define([comedilib_lt_revision], [1])
 m4_define([comedilib_lt_age], [10])
+# Set 'letter', normally empty.  See below for rules.
+m4_define([comedilib_version_letter], [])
 
 #libscxi c:r:a
 m4_define([scxi_lt_current], [9])
 m4_define([scxi_lt_revision], [0])
 m4_define([scxi_lt_age], [9])
 
-# comedilib version: major.minor.micro
+# comedilib library version: major.minor.micro
+# comedilib package version: major.minor.micro[letter]
 #
 # Currently:
 #  * 'major' may be incremented at the whim of the maintainers.
 #  * 'minor' is libtool 'current' minus the value of 'current' when major
 #    changed (comedilib_major_base_current).
 #  * 'micro' is libtool 'revision'.
+#  * 'letter' is normally absent and is removed if any of 'major', 'minor'
+#    or 'micro' are changed between releases.  Otherwise it is set if the
+#    only changes between releases are outside the library source code or
+#    language binding, for example the comedilib manual, "readme" files
+#    or sample configuration files.  When it needs to be set, it is set to
+#    'a' if previously absent, otherwise the next lower-case ASCII letter
+#    in the sequence.  (In the unlikely event that we we need to go beyond
+#    'z', append an extra letter.)
+#
+# Example package version sequence: 0.10.1, 0.10.1a, 0.10.1b, 0.10.2,
+# 0.10.2a, ..., 0.10.2z, 0.10.2za, 0,10.2.zb, 0.11.0.
 
 # Gentle reminder: The comedilib manual mentions the version of comedilib
 # it applies to.  This is done by setting the 'comedilib_version' entity
 # in "doc/comedilib.ent".  That needs to be edited manually as it is not
-# updated automatically.
+# updated automatically.  Policy: the version of the manual is usually only
+# updated if the contents have changed since the previous release.  In that
+# case, it is set to the comedilib package version.
 
 # Manually set 'comedilib_major_base_current' to new 'comedilib_lt_current'
 # whenever 'comedilib_version_major' is incremented below.
@@ -49,7 +65,11 @@ m4_define([comedilib_version_minor],
          [m4_eval(comedilib_lt_current - comedilib_major_base_current)])
 m4_define([comedilib_version_micro], [comedilib_lt_revision])
 m4_define([comedilib_pkg_version],
-         [comedilib_version_major.comedilib_version_minor.comedilib_version_micro])
+         [m4_join([],
+                  m4_join([.], comedilib_version_major,
+                          comedilib_version_minor,
+                          comedilib_version_micro),
+                  comedilib_version_letter)])
 
 AC_INIT([comedilib], [comedilib_pkg_version])
 AC_CANONICAL_TARGET([])