a question about archive

[subjugater]

I am now using a package written by someone else. I am following the README instruction enclosed in the parent folder to compile. The parent folder contains two subfolders, i.e. "f1" and "f2". I'll denote the parent folder by ../ in the following context.

Each of these two subfolders has its own makefile. In "f1", "makefilef1.mk" generates an archive "arch.a" in the parent folder, i.e. ../ as following

arch.a: $(LIB_OBJ)
        $(AR) $(ARFLAGS) ../arch.a $(LIB_OBJ)
	$(RANLIB) ../arch.a

Then in "f2" "makefilef2.mk" generates an archive with the same name "arch.a" in the ../ too as this (this part of codes is same as above):

arch.a: $(LIB_OBJ)
	$(AR) $(ARFLAGS) ../arch.a $(LIB_OBJ)
	$(RANLIB) ../arch.a

My question is: When I generate the second archive with the same name "arch.a" in the same folder, i.e. the parent folder ../, will the archive "arch.a" generated by "makefilef1.mk" be overwritten by the the one generated by "makefilef2.mk"? Or these two archives are just merged?

Thank you so much.

[subjugater]

bump up~

[helios]

This should be addressed in the README. If it isn't, then it's not important. Whatever result you get at the end of the process is the correct one.

[subjugater]

Hi helios,

I got everything right after following the instruction of README strictly. Any the README file doesn't explain what I asked.

Further questions:

1. Archive files can only help after the very first compilation, right?
2. How much can archive files help/speed up the following re-compilation? Should the help be significant?

Thanks a lot.

[Galik]

It think it depends on what flags are set in the variable $(ARFLAGS):

http://linux.die.net/man/1/ar

I would imagine the objects in the archive are updated with the newly compiled versions from each subdirectory.

[subjugater]

Galik,

Thank you for your response. Yes, you are right. The AR flag, i.e. ARFLAGS, is defined with "-r", which clearly indicates that everything new is appended at the end of the original archive file. Again, thanks.