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benobi

08-09-2005 04:55 PM

Makefile question - multiple compilation flags

I have the following code in a cpp file that I'm trying to compile

Code:

#include <iostream>



using std::cout;



int main()

{

        #if __DO_THIS__

        cout << "do this\n";

        #endif



        #if __DO_THAT__

        cout << "do that\n";

        #endif



        return 0;

}

And I'm trying to use this Makefile:

Code:

CXX = g++

CXXFLAGS = -Wall -c -D__DO_THIS__

CXXFLAGS2 = -Wall -c -D__DO_THAT__



OBJ_DIR =

OBJ_EXT = o86



SOURCES = main.cpp

OBJECTS = $(SOURCES:%.cpp=$(OBJ_DIR)%.$(OBJ_EXT))



main1: $(OBJECTS)

        $(CXX) -o $@ $(OBJECTS)



$(OBJ_DIR)%.$(OBJ_EXT): %.cpp

        $(CXX) $(CXXFLAGS) -o $@ $<



main2: $(OBJECTS)

        $(CXX) -o $@ $(OBJECTS)



$(OBJ_DIR)%.$(OBJ_EXT): %.cpp

        $(CXX) $(CXXFLAGS2) -o $@ $<

When I type "make main1" it compiles it using CXXFLAGS2, which I'm pretty sure it's because

Code:

$(OBJ_DIR)%.$(OBJ_EXT): %.cpp

was used twice. Is there a better/correct way to write this makefile so that I can compile the code with one set of compiler flags and then another set of compiler flags?

jonaskoelker

08-09-2005 09:36 PM

Moving the decision (between THIS and THAT) into main[12] and/or using variables spring to mind. RTM.

hth --Jonas

benobi

08-10-2005 11:14 AM

I can't use variables since this is for a larger program I'm trying to write, I just simplified it so it'd be easier to understand on this forum. Obviously this is a trivial example. One version of the program runs on one way, the other version runs on another way, so instead of making two different copies of the program where most of the files are the same except for this one, I want to be able to set a compiler flag so that it compiles and performs one way (different function calls and included files) or the other way. I don't want to edit the .cpp file everytime I want to build it a certain way. Just want to type make main1 or make main2 and let the computer do the rest.

jonaskoelker

08-10-2005 12:07 PM

I meant *makefile* variables.

benobi

08-10-2005 01:00 PM

Ok thanks I see how I can use %if $(VARIABLE), %else, %elif, etc, but how do i pass the string "main1" and "main2" from the command prompt into these variables?

jonaskoelker

08-10-2005 02:08 PM

short example:

Code:

do=

main:

\t      wtf is $(do)

Code:

$ make do=this

wtf is this

(...)

$ make do=that

wtf is that

(...)

$ exit

hth --Jonas

benobi

08-11-2005 01:11 PM

Still not 100% sure how the syntax works. I have this:

Code:

CXX = g++

CXXFLAGS = -Wall -c -D__DO_THIS__

CXXFLAGS2 = -Wall -c -D__DO_THAT__



OBJ_DIR =

OBJ_EXT = o86



SOURCES = main.cpp

OBJECTS = $(SOURCES:%.cpp=$(OBJ_DIR)%.$(OBJ_EXT))



do=



main: $(OBJECTS)

        $(CXX) -o $@ $(OBJECTS)

        $(OBJ_DIR)%.$(OBJ_EXT): %.cpp

        

        %if $(do) == 1

                $(CXX) $(CXXFLAGS) -o $@ $<

        %elif $(do) == 2

                $(CXX) $(CXXFLAGS2) -o $@ $<

        %endif



SOURCES2 = different_program.cpp

OBJECTS2 = $(SOURCES2:%.cpp=$(OBJ_DIR)%.$(OBJ_EXT))



different_program:

        $(CXX) -o $@ $(OBJECTS2)

        $(OBJ_DIR)%.$(OBJ_EXT): %.cpp

        

        %if $(do) == 1

                $(CXX) $(CXXFLAGS) -o $@ $<

        %elif $(do) == 2

                $(CXX) $(CXXFLAGS2) -o $@ $<

        %endif

It's telling me there's no rule to make main.o86. Also from the command prompt do I type:

Code:

$ make main do=1

$ make different_program do=1

Since eventually I want the Makefile to compile several programs, so I want to be able to differentiate between them.

jonaskoelker

08-11-2005 01:42 PM

I was just thinking:

Code:

CXXFLAGS = -wall -c -D__DO_$(do)__

RTM to see if there's a toupper or similar. RTM in any case.

hth --Jonas

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