常用的C/C++工程Makefile模板

在Linux下做开发难免要接触makefile，整个项目的构建都依赖于它。100个developer有100种makefile的写法，在一个较大的项目中，各种各样的makefile无论在开发、后期维护还是整个系统的持续集成都是一个负担。

有幸参与重构一个遗留系统的makefile，以下是一些心得和一个makefile模板。
重构目的：
1.清晰易懂、容易维护
2.方便系统的持续集成
重构原则：
1.子模块makefile模板化
2.外部依赖、通用宏定义集中化
3.中间和最终输出集中，便于系统构建

下面是总结出的一个makefile模板，我在日常的开发中都用它，其中加入了详细的注释。

#Get the ROOT_PATH which common files located, assuming this makefile located in $(ROOT_PATH)/src/sub_module
ROOT_PATH = $(shell cd ../..; pwd)

#Where define the path of third party modules
include $(ROOT_PATH)/path

#Where define common macros such as CC=gcc, CXX=g++ and so on
include $(ROOT_PATH)/common

#Set target output path and the path of intermidiate object
#The path macros should include in $(ROOT_PATH)/path
OUT_PATH = $(OUTPUT_PATH)/submodule
OBJ_PATH = $(TMPOBJ_PATH)/submodule
TARGET = $(OUT_PATH)/targe

#If the targe is share object then set corresponding flags
#which should define in $(ROOT_PATH)/common
CFLAGS += $(CFLAGS_SO)
LDFLAGS += $(LDFLAGS_SO)
#Custom Predefines
CFLAGS += -DXXXXXXXX
CFLAGS += -DYYYYYYYY
#Dependent header files
#The path macros should include in $(ROOT_PATH)/path
CFLAGS += -I. /
-I$(XXXX_INC) /
-I$(YYYY_INC) /
-I$(ZZZZ_INC)
#Dependent libraries
#The path macros should include in $(ROOT_PATH)/path
LDFLAGS += -L$(XXXX_LIB) -lxxxx /
-L$(YYYY_LIB) -lyyyy

#Set CPP source directory
CPP_SRCDIR = .
#Or set specific CPP Source files
ADDITIONAL_CPP_SOURCES = /
$(PATH_A)/a.cpp /
$(PATH_B)/b.cpp

#Traverse every directory in $(CPP_SRCDIR), and find every cpp file
CPP_SOURCES = $(foreach d,$(CPP_SRCDIR),$(wildcard $(d)/*.cpp) ) $(ADDITIONAL_CPP_SOURCES)
#Traverse every cpp file in $(CPP_SOURCES) and get corresponding object file(.o)
CPP_OBJFILES = $(patsubst %.cpp,$(OBJ_PATH)/%.o,$(notdir $(CPP_SOURCES)))

#Set C source directory
C_SRCDIR =
#Or set specific C Source files
ADDITIONAL_C_SOURCES = /
$(PATH_A)/a.c /
$(PATH_B)/b.c

#C Source files
C_SOURCES = $(foreach d,$(C_SRCDIR),$(wildcard $(d)/*.c) ) $(ADDITIONAL_C_SOURCES)
C_OBJFILES = $(patsubst %.c,$(OBJ_PATH)/%.o,$(notdir $(C_SOURCES)))

#Set vpath where to find these types of files
vpath %.cpp $(dir $(CPP_SOURCES))
vpath %.c $(dir $(C_SOURCES))
vpath %.o $(OBJ_PATH)

#The first target to be executed
all: target

target: $(TARGET)

#Static dependecy pattern
#$(OBJ_PATH)/%.o define the pattern of target and %.c or %.cpp is the final dependency
$(C_OBJFILES): $(OBJ_PATH)/%.o: %.c
-mkdir -p $(OBJ_PATH)
$(CXX) -c $(CFLAGS) -o $@ $<

$(CPP_OBJFILES): $(OBJ_PATH)/%.o: %.cpp
-mkdir -p $(OBJ_PATH)
$(CXX) -c $(CFLAGS) -o $@ $<

$(TARGET): $(CPP_OBJFILES) $(C_OBJFILES)
-mkdir -p $(OUT_PATH)
$(CXX) -o $@ $^ $(LDFLAGS)

clean:
-rm -rf $(OBJ_PATH)
-rm -f $(TARGET)