I guess but this is also portable and more people know how to extend it:

    $ cat Makefile 
    SRCS = foo.cpp bar.cpp baz.cpp
    OBJS = $(SRCS:.cpp=.o)
    PROG = app
    EXT  =
    
    .PHONEY = all clean
    
    all : $(PROG)
    
    LDLIBS = $(OBJS)
    
    $(PROG) : $(PROG:$(EXT)=.cc) $(OBJS)
    
    clean :
            rm -f $(PROG) $(OBJS)
    $ make SRCS="`echo *.cpp`" clean all
    rm -f app a.o b.o c.o
    c++ -O2 -pipe -c a.cpp -o a.o
    c++ -O2 -pipe -c b.cpp -o b.o
    c++ -O2 -pipe -c c.cpp -o c.o
    c++ -O2 -pipe  app.cc a.o b.o c.o -o app
    $