How to link only some files to objects with Makefile (g++)?

Question

I have a Makefile that compiles the source to object files, and it works:

$(OBJ_DIR)/%.o: $(SRC_DIR)/%.cpp
    g++ $(FLAGS) $(INCLUDES) -c -o $@ $<

but it includes all the files from my src directory. Say I have some file (eg "x.cpp") that I don't want as a part of my compilation. I'd like to manually specify only some files to compile into objects. For example,

SRC = src/one.cpp src/two.cpp
OBJ = obj/one.o obj/two.o
$(OBJ_DIR)/%.o: $(SRC)
    g++ $(FLAGS) $(INCLUDES) -c -o $@ $<

I'd get one.o, two.o, but NOT xo Is this possible somehow?

Answer 1

Define a list of modules, construct the list of objects you actually want:

MODULES = one two
OBJECTS = $(addprefix ${OBJ_DIR}/, $(addsuffix .o, ${MODULES}))

all : ${OBJECTS}

Restrict the rule to those in the list:

${OBJECTS}: $(OBJ_DIR)/%.o: $(SRC_DIR)/%.cpp
        g++ $(FLAGS) $(INCLUDES) -c -o $@ $<