Some improvements to the Makefile.

Makefile

@@ -2,9 +2,11 @@ SRC = src
 TEST = test
 BUILDDIR = build
 DISTDIR = dist
+COVERDIR = coverage
+SRCFILES := $(shell find $(SRC) -type f)
 
 # stupid distutils, it's broken in so many ways
-SUBBUILDDIR = $(shell python -c 'import distutils.util, sys; \
+SUBBUILDDIR := $(shell python -c 'import distutils.util, sys; \
 	      print "lib.%s-%s" % (distutils.util.get_platform(), \
 	      	sys.version[0:3])')
 PYTHON25 := $(shell python -c 'import sys; v = sys.version_info; \
@@ -16,11 +18,13 @@ else
 BUILDDIR := $(BUILDDIR)/lib
 endif
 
-COVERAGE = $(or $(shell which coverage), $(shell which python-coverage), \
-	   coverage)
+COVERAGE := $(or $(shell which coverage), $(shell which python-coverage), \
+	    coverage)
 
-all:
+all: build_stamp
+build_stamp: $(SRCFILES)
 	./setup.py build
+	touch $@
 
 install: all
 	./setup.py install
@@ -32,25 +36,32 @@ test: all
 		PYTHONPATH="$(BUILDDIR)" $$i || retval=$$?; \
 		done; exit $$retval
 
-coverage: all
-	rm -f .coverage
+coverage: coverage_stamp
+	$(COVERAGE) -r -m `find "$(BUILDDIR)" -name \\*.py -type f`
+
+coverage-report: coverage_stamp
+	rm -rf $(COVERDIR)
+	$(COVERAGE) -b -d $(COVERDIR) `find "$(BUILDDIR)" -name \\*.py -type f`
+	@echo "Coverage report created in $(COVERDIR)/index.html"
+
+coverage_stamp: build_stamp
 	for i in `find "$(TEST)" -perm -u+x -type f`; do \
 		set -e; \
 		PYTHONPATH="$(BUILDDIR)" $(COVERAGE) -x $$i; \
 		done
 	$(COVERAGE) -c
-	$(COVERAGE) -r -m `find "$(BUILDDIR)" -name \\*.py -type f`
-	rm -f .coverage
+	touch $@
 
 clean:
 	./setup.py clean
-	rm -f `find -name \*.pyc` .coverage *.pcap
+	rm -f `find -name \*.pyc` .coverage *.pcap *_stamp
+	rm -rf $(COVERDIR)
 	$(MAKE) -C $(CURDIR)/benchmarks/ clean
 
 distclean: clean
 	rm -rf "$(DISTDIR)"
 
-MANIFEST:
+MANIFEST: distclean
 	find . -path ./.hg -prune -o -path ./build -prune -o \
 		-name \*.pyc -prune -o -name \*.swp -prune -o \
 		-name MANIFEST -prune -o -type f -print | \