Makefiles, what are you doing with them?

Brett Schuchert — Wed, 27 Jan 2010 09:02:00 -0600

Half a year ago, I took some exercises written in Java and ported them to C++. At that time I punted on writing makefiles and decided to reply on an IDE (Visual Studio). That worked fine but recently we almost had a customer that was going to take this class and, bless their heart, use the command line.

Turns out they are going to use visual studio, so I can shelve this, but I figured I’d get feedback on what I have created for a makefile. Since I have not written a makefile for 12ish years, I figured things have changed. They have, but I suspect they have even more.

What follows are my environment assumptions and the makefile. I’d appreciate any suggestions.

FWIW, I wrote this makefile because it turns out fully building all files takes longer than just building what has changed. I know this seems obvious, but it is not always the case with small projects like this. There is some point where the project becomes big enough to warrant dependency-based building. The exercise meets that criteria. Sometimes the time taken to evaluate build changes is enough overhead that it can be safely removed in lieu of a full build. This is a consideration when creating custom build files for legacy-based refactoring efforts.

Environment

Generic Unix
zsh – though any shell will do really
g++
gnu make
This source base will still be used in Visual Studio but not this makefile
CppUTest used for unit testing tool
Provide default location for CppUTest, which can be overridden by environment variable
Boost library installed in /usr/local/include and /usr/local/lib (reasonable assumption or should I go ahead and allow this to be configured easily in the makefile – what’s your opinion?)
Project is small enough that all headers and source files are in the same directory (should I build the .o’s and put them in another directory to hide them?)

Current Makefile

ifdef CPP_U_TEST
    CppUTest_base = $(CPP_U_TEST)
else
    CppUTest_base = $(wildcard ~/src/cpputest)
endif

LIB_DIRS = -L$(CppUTest_base)/lib
INC_DIRS = -I$(CppUTest_base)/include
LIBS = -lCppUTest -lboost_date_time -lboost_regex -lboost_thread
CFLAGS = -g $(INC_DIRS) 
LDFLAGS = $(LIB_DIRS) $(LIBS)
CC = g++
SRCS := $(wildcard *.cpp)
OBJS = $(SRCS:.cpp=.o)
OUT = run_all_tests
DEP_DIR = dependencies

all: $(OBJS)
    $(CC) $(CFLAGS) $(LDFLAGS) -o $(OUT) $(OBJS)

clean:
    @rm -rf $(DEP_DIR) $(OBJS) $(OUT)

-include $(SRCS:.cpp=$(dep_dir)/.d)

.cpp.o:
    @if [ ! -d $(DEP_DIR) ] ; then mkdir $(DEP_DIR) ; fi
    $(CC) -c $(CFLAGS) -o $@ $< 
    @$(CC) -MM $(CFLAGS) $*.cpp > $(DEP_DIR)/$*.d

Object Mentor Blog: Tag makefile

Makefiles, what are you doing with them?