Question about MAKE utility

[Wojtek Dudczak]

Hi all,

Make has double suffix interference rule .cpp.o for building .o files from .cpp files. This rule looks like:

.cpp.o
$(CXX) $(CXXFLAGS) -c $<

But this rue produces .o file in the same directory where .cpp source file is located, and works only when .o and .cpp are in the same directory. Is it possible to define similiar rule, that will allow me to have source code and object files in separate directories?

Thank You in advance

[Ceesjan van Hattum]

As i can see in 'man make', it is possible to execute multiple commands in a rule; like:

.y.o:
$(YACC) $(YFLAGS) $<
$(CC) $(CFLAGS) -c y.tab.c
rm y.tab.c
mv y.tab.o $@

So, can you try to do:
.cpp.o
$(CXX) $(CXXFLAGS) -c $<
mkdir ./newdir
mv *.o ./newdir/

Please let me know your findings..
Regards,
Ceesjan

[Tom Maloy]

You may need to use nmake or gmake, or try to write some of your own inference rules.

Note that Ceesjan's solution will cause you to do a rebuild of every *.cpp file every time you run make, because make will not look in the directory where the *.o files are.

Tom

[H.Merijn Brand (procura]

rules always end with a colon (':') in all versions and ports of make. I guess that your real makefile indeed has

.cpp.o:

with a colon.

A much better make is the GNU make. Binaries are available from a HP porting center or from https://www.beepz.com/personal/merijn

[Wojtek Dudczak]

Ceesjan were right, but as Tom said: this solution would cause to rebuild all .cpp files every time make is launched. And of course I omitted colon in my example by mistake.

Thank you guys for your assistance.

Wojtek

[Sergiy Nevstruyev]

Hi Wojtek,

you can try to use the following one. Looks ugly but works :-).

################################

OD = ./obj
OD_OBJS = $(OD)/test.o
OBJS = test.o

main: moveobjs $(OBJS) removeobjs

moveobjs:
cp $(OD_OBJS) . || echo ""

.c.o:
gcc -o $(OD)/$@ -c $<

removeobjs:
rm $(OBJS)

[Ian Lochray · Accepted solution]

Stefan Paitoni has answered this in another thread. The solution is:

VPATH=:

.cpp.o :
...

[Wojtek Dudczak]

Best solution was with VPATH

Thanks again