Compile and link when dependent header file changed in other directory

Question

I have 3 questions about compiling and linking my project in fewer steps...

First, my project looks like: ( I use Watcom C to compile//link my project )

Directory 'MyProject' contains 3 sub directories for different modules and some files:

• directory 'A' ( a.h and a.c included )
• directory 'B' ( b.h and b.c included )
• directory 'C' ( c.h and c.c included )
• my.c and my.h
• my.lnk
• makefile

And within each sub directory there is one corresponding makefile...

[Q1] Assume I update a.h in directory A and a.h is referenced by b.c in directory B, then my original steps will be:

1. compile in directory A ( obj and lib generated...)
2. compile in directory B ( obj and lib generated...)
3. back to directory MyProject then compile and link

Can I just take one step to cover above ?

[Q2] If I want to ignore all existing obj/lib and rebuild all, how to do it ?

• I know this takes time but sometimes "kill and rebuild" will be better...

[Q3] If my.h is updated and it is referenced by a.c,b.c, and c.c...

Can I just take one step to cover above ?

[My makefile in sub directory looks like]

INCLUDE1 = -ic:\watcom\h
OBJECTS1 = a.obj
CFLAGS   = -zq -mf -oxsbl $(INCLUDE1)
DEST     = a.exe
COMPILER = wpp386

.erase # special cmd, tell wmake to "erase" target if make is not successful
.cpp.obj: .AUTODEPEND
      $(COMPILER) $(CFLAGS) $<

$(DEST) : $(OBJECTS1) makefile

[My makefile in main directory looks like]

INCLUDE1 = -i=c:\myproj\my -i=c:\watcom\h 
OBJECTS1 = my.obj
CFLAGS   = -zq -fp6 -mf -6r -s -oxsbl $(INCLUDE1)
DEST     = my.exe
COMPILER = wpp386
LINKER   = wlink
LNK_FILE = my.lnk

.erase # special cmd, tell wmake to "erase" target if make is not successful

.cpp.obj: .AUTODEPEND
      $(COMPILER) $(CFLAGS) $<


$(DEST) : $(OBJECTS1) makefile my.lnk
      $(LINKER) @$(LNK_FILE)

[Update 1]

I use wpp386 as compiler and it is watcom c++ tool.

To build the target I use one batch file to compile cpp file:

@echo off
del a1.lib
del *.err
wmake -h
wlib -q a1.lib + a.obj

del *.obj

• I can successfully compile cpp file and everything is fine.
• In directory B, I use the same way(batch file+makefile) to compile b.cpp

To sum up my project works and the reason why I ask is to find "faster compiling/linking sequence" if I just update some header file...

I tried add the command ehco hello to the rule $(DEST) and found it was ok. Then use echo $(MAKE) and got:

...
echo C:\WATCOM\BINW\WMAKE.EXE
C:\WATCOM\BINW\WMAKE.EXE
...

Thanks !

Answer 1

I'm not familiar with your compiler, so I can't see how these makefiles work, so we'll have to take this one step at a time.

1) when you go into a subdirectory A, what command do you use to build the targets? Does it work? How about in subdirectory B?

2) In the main makefile, can you add a command, like echo hello to the $(DEST) rule? If that works, try echo $(MAKE).

EDIT:

Non-GNU versions of Make are troublesome, but we'll see what we can do.

Try editing the makefile in subdir A:

INCLUDE1 = -ic:\watcom\h
OBJECTS1 = a.obj
CFLAGS   = -zq -mf -oxsbl $(INCLUDE1)
DEST     = a1.lib # NOTE THIS CHANGE
COMPILER = wpp386

.erase # special cmd, tell wmake to "erase" target if make is not successful
.cpp.obj: .AUTODEPEND
      $(COMPILER) $(CFLAGS) $<

$(DEST) : $(OBJECTS1) makefile
      wlib -q $@ + $(OBJECTS1)
      del $(OBJECTS1)

Instead of the batch file, just run make -h. This should rebuild the library (if the library needs rebuilding). If it works, try moving up into MyProject and running make -h -C A. This should execute the makefile in A and rebuild the library there (unless WMAKE has some other syntax).

If that works, try making the same changes in B, then editing the $(DEST) rule in the main makefile:

$(DEST) : $(OBJECTS1) makefile my.lnk
    $(MAKE) -h -C A
    $(MAKE) -h -C B
    $(LINKER) @$(LNK_FILE)

Cross your fingers and run make -h. This should rebuild both libraries, compile, link, and solve Q1...