用于将对象和依赖文件自动放置在单独文件夹中的Makefile

Question

I would like to place the object files of the compiler in a different folder than the source files. I made it working, when using the same folder structure as the way my source code is build up, but this is not the solution i am looking for.

What I would prefer is the following:

Sources:

src/main.cpp
src/myClass/myClass.cpp

Object:

obj/main.o
obj/myClass.o

Dependencies

dep/main.d
dep/main.d

What I have until now is the following

VARIABLES

$(OBJLIST)=obj/main.o obj/myClass.o
$(SRCDIR)=src
$(OBJDIR)=obj

LINKER

$(PROJECT): $(OBJLIST)
    $(CXX) $(OBJLIST) $(LIBS) -o $@

COMPILER and here is my problem

This is what is working

$(OBJDIR)/%.o: $(SRCDIR)/%.cpp
    @mkdir -p $(DEPDIR) $(OBJDIR)
    $(CXX) $(CPPFLAGS) -c $< -o $@
    $(CXX) $(CPPFLAGS) -MM -MT 1_obj/main.o 0_src/main.cpp -o 2_dep/main.dep
$(OBJDIR)/%.o: $(SRCDIR)/myClass/%.cpp
    @mkdir -p $(DEPDIR) $(OBJDIR)
    $(CXX) $(CPPFLAGS) -c $< -o $@
    $(CXX) $(CPPFLAGS) -MM -MT 1_obj/myClass.o 0_src/myClass/myClass.cpp -o 2_dep/myClass.dep

I also have an object called SRCDIRS containing:

SRCDIRS
    ./
    ./myClass

So i hoped I could merge the compile-definitions to something like

$(OBJDIR)/%.o: $(SRCDIR)/$(SRCDIRS)/%.cpp
    @mkdir -p $(DEPDIR) $(OBJDIR)
    $(CXX) $(CPPFLAGS) -c $< -o $@
    $(CXX) $(CPPFLAGS) -MM -MT $@ @< -o $(DEPDIR)/$(notdir $(basename $<).dep)

I hoped this would generalize for both possibilities, but somehow, it seams it does not loop through SRCDIRS and check for any match.

Answer 1

You can do it with vpath . Be aware that VPATH can only be used to find source files.

So, something like this:

VPATH = $(SRCDIRS)

$(OBJDIR)/%.o : %.c
        ...

is all you need.