Makefile - Build CPPs with each one has a main for apps

There always are cpp files and each of them has a main function as a standalone app each. For example, in my folder DesignPatterns I have files factory_example.cpp and command.cpp, they ready to be built into factory_example.exe and command.exe over Lunix. So that the following Makefile will helpful on the points.

.PHONY: all clean pre-build

SRCS            = $(wildcard *.cpp)
BINS            = $(patsubst %.cpp,%.exe,$(SRCS))

LDFLAGS         = -L.
LDLIBS          = -lpthread

CPPFLAGS        = -D_DEBUG
CXXFLAGS        = -O3 -g

all: pre-build $(BINS)

pre-build:
	@echo "#-------------------------------------------------------------------------------"
	@echo "#                     Build Design Patterns Examples"
	@echo "#-------------------------------------------------------------------------------"

%.exe: %.o
	@echo ""
	@echo "# Build $@"
	$(CXX) $(CPPFLAGS) $(LDFLAGS) $^ -o $@ $(LDLIBS)
	@echo "#-------------------------------------------------------------------------------"

%.o: %.cpp
	$(CXX) -c $(CXXFLAGS) $(CPPFLAGS) $^ -o $@

tar: 
	@echo "#-------------------------------------------------------------------------------"
	@echo "#                            Build Tarball"
	@echo "#-------------------------------------------------------------------------------"
	rm -rf DesignPatterns && mkdir DesignPatterns
	cp $(SRCS) Makefile DesignPatterns
	tar cvf design_patterns_$(shell date +"%Y%m%d").tar DesignPatterns
	rm -rf DesignPatterns

clean:
	$(RM) $(BINS) *.o