Improving user experience.

cpp/helloworld/Makefile

@@ -29,19 +29,82 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #
 
-CXX=g++
-CPPFLAGS=-I/usr/local/include -pthread
-CXXFLAGS=-std=c++11
-LDFLAGS=-L/usr/local/lib -lgrpc -lgrpc++ -lprotobuf -lpthread -ldl
+CXX = g++
+CPPFLAGS = -I/usr/local/include -pthread
+CXXFLAGS = -std=c++11
+LDFLAGS = -L/usr/local/lib -lgrpc -lgrpc++ -lprotobuf -lpthread -ldl
+PROTOC = protoc
+GRPC_CPP_PLUGIN = grpc_cpp_plugin
+GRPC_CPP_PLUGIN_PATH ?= `which $(GRPC_CPP_PLUGIN)`
 
-all: greeter_client greeter_server
+PROTOS_PATH = ../../protos
+
+vpath %.proto $(PROTOS_PATH)
+
+all: system-check greeter_client greeter_server
 
 greeter_client: helloworld.pb.o greeter_client.o
-	$(CXX) $(CPPFLAGS) $^ $(LDFLAGS) -o $@
+	$(CXX) $^ $(LDFLAGS) -o $@
 
 greeter_server: helloworld.pb.o greeter_server.o
-	$(CXX) $(CPPFLAGS) $^ $(LDFLAGS) -o $@
+	$(CXX) $^ $(LDFLAGS) -o $@
+
+%.pb.cc: %.proto
+	$(PROTOC) -I $(PROTOS_PATH) --cpp_out=. --grpc_out=. --plugin=protoc-gen-grpc=$(GRPC_CPP_PLUGIN_PATH) $<
 
 clean:
-	rm -f *.o greeter_client greeter_server
+	rm -f *.o *.pb.cc *.pb.h greeter_client greeter_server
 
+
+# The following is to test your system and ensure a smoother experience.
+# They are by no means necessary to actually compile a grpc-enabled software.
+
+PROTOC_CMD = which $(PROTOC)
+PROTOC_CHECK_CMD = $(PROTOC) --version | grep -q libprotoc.3
+PLUGIN_CHECK_CMD = which $(GRPC_CPP_PLUGIN)
+HAS_PROTOC = $(shell $(PROTOC_CMD) > /dev/null && echo true || echo false)
+ifeq ($(HAS_PROTOC),true)
+HAS_VALID_PROTOC = $(shell $(PROTOC_CHECK_CMD) 2> /dev/null && echo true || echo false)
+endif
+HAS_PLUGIN = $(shell $(PLUGIN_CHECK_CMD) > /dev/null && echo true || echo false)
+
+SYSTEM_OK = false
+ifeq ($(HAS_VALID_PROTOC),true)
+ifeq ($(HAS_PLUGIN),true)
+SYSTEM_OK = true
+endif
+endif
+
+system-check:
+ifneq ($(HAS_VALID_PROTOC),true)
+	@echo " DEPENDENCY ERROR"
+	@echo
+	@echo "You don't have protoc 3.0.0 installed in your path."
+	@echo "Please install Google protocol buffers 3.0.0 and its compiler."
+	@echo "You can find it here:"
+	@echo
+	@echo "   https://github.com/google/protobuf/releases/tag/v3.0.0-alpha-1"
+	@echo
+	@echo "Here is what I get when trying to evaluate your version of protoc:"
+	@echo
+	-$(PROTOC) --version
+	@echo
+	@echo
+endif
+ifneq ($(HAS_PLUGIN),true)
+	@echo " DEPENDENCY ERROR"
+	@echo
+	@echo "You don't have the grpc c++ protobuf plugin installed in your path."
+	@echo "Please install grpc. You can find it here:"
+	@echo
+	@echo "   https://github.com/grpc/grpc"
+	@echo
+	@echo "Here is what I get when trying to detect if you have the plugin:"
+	@echo
+	-which $(GRPC_CPP_PLUGIN)
+	@echo
+	@echo
+endif
+ifneq ($(SYSTEM_OK),true)
+	@false
+endif