Re: How to automatically update a automatically generated dependence file?

[Peng Yu]

On Fri, Oct 24, 2008 at 12:45 AM, Peng Yu <address@hidden> wrote:
> On Thu, Oct 23, 2008 at 8:59 PM, Greg Chicares <address@hidden> wrote:
>> On 2008-10-23 23:49Z, Peng Yu wrote:
>> [...issues with generating dependency files]
>>
>> http://make.paulandlesley.org/autodep.html
>
> Are you referring to this section?
> Avoiding ``No rule to make target ...'' Errors
>
> I'm not sure how to adapt it to my problem, as my problem arises when
> the dependence file is modified externally. Would you please let me
> know how to change my Makefile?

I guess. I figure out how to use it. See below for the source code and
the Makefile. After running make, I can change nothing3.hpp to
nothing2.hpp. The make still runs after the modification.

sed -e 's/#.*//' -e 's/^[^:]*: *//' -e 's/ *\\$$//' -e '/^$$/ d' -e
's/$$/ :/' < $*.d >> $*.P; \

But the above line is too hard to understand. Can somebody explain
what eche command after -e does?

The first one  's/#.*//'  seems removes the comment, right? But would
g++ -MM  generate comments?

Thanks,
Peng


=================================
$ for f in *.cpp *.hpp; do echo //$f; cat $f; done; echo \#Makefile;
cat Makefile
//main.cpp
#include "print.hpp"

int main() {
  print();
}
//nothing1.hpp
#include "nothing3.hpp"
//nothing3.hpp
//print.hpp
#include "nothing1.hpp"
#include <iostream>

void print() {
  std::cout << "Hello World" << std::endl;
}
#Makefile
.PHONY: all

all: main.exe

main.exe : main.o
        $(CC) $< $(LOADLIBES) $(LDLIBS) -o $@

SRC = main.cpp

MAKEDEPEND = g++ -MM $(CPPFLAGS) -o $*.d $<

%.o: %.cpp
        $(MAKEDEPEND); \
                cp $*.d $*.P; \
                sed -e 's/#.*//' -e 's/^[^:]*: *//' -e 's/ *\\$$//' -e
'/^$$/ d' -e 's/$$/ :/' < $*.d >> $*.P; \
                rm -f $*.d
        $(COMPILE.c) -o $@ $<

-include $(SRC:.cpp=.P)

clean:
        @$(RM) *.o *.exe *.d *.P