[apparmor] [PATCH v3 3/5] Makefile: Convert shell variables into reusable make variables

[Tyler Hicks]

Turn REPO_VERSION and SNAPSHOT_DIR into make variables that may be
reused by future targets that specify the snapshot target as a
prerequisite. This prevents us from having to repeatedly call out to
potentially slow commands on bound bzr branches, such as the bzr
version-info command stored in the REPO_VERSION_CMD make variable.

The new REPO_VERSION make variable is turned into a "simply expanded"
variable as to not require a callout to bzr each time it is expanded.

The SNAPSHOT_DIR shell variable is renamed to SNAPSHOT_NAME as a make
variable. The new name may be slightly more descriptive in the future as
the variable will be reused in other ways besides a simple directory
name.

Signed-off-by: Tyler Hicks <tyhicks at canonical.com>
---

* Changes since v2:
  - Move REPO_VERSION and SNAPSHOT_NAME make variable definitions into the
    snapshot target instead of using the 'target-specific' variable technique.
    The reason is because target-specific simply expanded make variables are
    always evaluated, no matter if the target was specified or not. That was
    causing REPO_VERSION_CMD to always be ran, even when the snapshot target
    was not in use, which is slow on bound bzr branches.

 Makefile | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/Makefile b/Makefile
index b9ed3b3..24cc2d2 100644
--- a/Makefile
+++ b/Makefile
@@ -45,11 +45,11 @@ tarball: clean
 
 .PHONY: snapshot
 snapshot: clean
-	REPO_VERSION=`$(value REPO_VERSION_CMD)` ; \
-	SNAPSHOT_DIR=apparmor-${VERSION}~$${REPO_VERSION} ;\
-	make export_dir __EXPORT_DIR=$${SNAPSHOT_DIR} __REPO_VERSION=$${REPO_VERSION} ; \
-	make setup __SETUP_DIR=$${SNAPSHOT_DIR} ; \
-	tar ${TAR_EXCLUSIONS} -cvzf $${SNAPSHOT_DIR}.tar.gz $${SNAPSHOT_DIR} ;
+	$(eval REPO_VERSION:=$(shell $(value REPO_VERSION_CMD)))
+	$(eval SNAPSHOT_NAME=apparmor-$(VERSION)~$(REPO_VERSION))
+	make export_dir __EXPORT_DIR=${SNAPSHOT_NAME} __REPO_VERSION=${REPO_VERSION} ; \
+	make setup __SETUP_DIR=${SNAPSHOT_NAME} ; \
+	tar ${TAR_EXCLUSIONS} -cvzf ${SNAPSHOT_NAME}.tar.gz ${SNAPSHOT_NAME} ;
 
 
 .PHONY: export_dir
-- 
2.5.0