Improved version control

subconvert_version.sh script checks for Subconvert version in the following order:
1) .tarball-version file contents (only generated for dist tarballs)
2) git describe
3) fallback version (currently 1.x-unknown)

Additionaly, it is invoked every time make is called and version.py __version__ variable is changed
with sed (unfortunate hack). It means that version.py will not take into account @PACKAGE_VERSION@
variable.

Author: Michał Góral

Makefile.am

@@ -17,13 +17,16 @@ EXTRA_DIST = \
 	CHANGELOG \
 	resources.qrc \
 	$(subconvert_SCRIPTS) \
-	$(desktop_DATA)
+	$(desktop_DATA) \
+	tools/subconvert_version.sh
 
 SUBCONVERT_DIR = ./subconvert
 COVERAGE_DIR = "coverage"
+VERSION = $(shell sh tools/subconvert_version.sh)
 
 gen:
 	$(PYRCC) -py3 -o $(SUBCONVERT_DIR)/resources.py resources.qrc
+	$(SED) -i 's/__version__ = .\+/__version__ = "$(VERSION)"/' subconvert/utils/version.py
 
 test: gen
 	@nosetests3 -v
@@ -45,6 +48,9 @@ install-data-hook:
 	cd $(DESTDIR)$(bindir) && \
 		$(LN_S) $(DESTDIR)$(datadir)/subconvert/subconvert.py subconvert
 
+dist-hook:
+	echo $(VERSION) > $(distdir)/.tarball-version
+
 reinstall:
 	make uninstall
 	make install

configure.ac

@@ -1,4 +1,4 @@
-AC_INIT([Subconvert], [m4_esyscmd_s([git describe --abbrev=4 --dirty --always --tags])], [https://github.com/mgoral/subconvert/issues])
+AC_INIT([Subconvert], [m4_esyscmd_s([sh tools/subconvert_version.sh])], [https://github.com/mgoral/subconvert/issues])
 AM_INIT_AUTOMAKE([foreign -Wall])
 
 AC_PREFIX_DEFAULT([/usr])
@@ -27,6 +27,11 @@ GETTEXT_PACKAGE=AC_PACKAGE_TARNAME
 AC_SUBST(GETTEXT_PACKAGE)
 AC_DEFINE_UNQUOTED(GETTEXT_PACKAGE,"$GETTEXT_PACKAGE", [gettext package])
 
+AC_CHECK_PROGS([SED], [sed], [:])
+if test "$SED" = :; then
+    AC_MSG_ERROR([Could not find program: sed])
+fi
+
 AC_CHECK_PROGS([PYRCC], [pyrcc4], [:])
 if test "$PYRCC" = :; then
     AC_MSG_ERROR([Could not find program: pyrcc4])

tools/subconvert_version.sh

@@ -0,0 +1,32 @@
+#!/bin/sh
+
+# Very simple version generator
+# First, we'll check for .tarball-version file (present only in dist tarballs). If it exists, we'll
+# take version number from there.  Second, we'll try to create git-based version and use it. If all
+# methods above fail, we'll set some kind of fallback version number.
+#
+# Version number is changed in subconvert/utils/version.py every time make is invoked, so
+# Subconvert will always display a proper version number. It's a little hacky, but it works.
+
+VERSION_FILE=".tarball-version"
+VERSION=""
+FALLBACK="1.x-unknown"
+
+nl='
+'
+
+if [ -f $VERSION_FILE ]; then
+    VERSION=`cat $VERSION_FILE` || VERSION=""
+fi
+
+if [ "$VERSION" = "" ]; then
+    if [ -d .git ]; then
+        VERSION=`git describe --abbrev=4 --dirty --always --tags`
+    fi
+fi
+
+if [ "$VERSION" = "" ]; then
+    VERSION=$FALLBACK
+fi
+
+echo $VERSION | tr -d "$nl"