Re: Object files automatically deleted by pattern rule

[Adam Lichtl]

If possible, I'd like to preserve a class of files matching a pattern 
(such as all object files).  I agree that I don't want them to be 
preserved if the build is interrupted.  Would this do the trick?:

OBJ := hello.o

.SECONDARY: $(OBJ)

Or is there some more suave trick where I don't have to compile a list 
of all of my object files?  This solution is fine, though, because my 
production Makefile already does have a list of the objects which it 
uses in the "clean" target.

-Adam

Paul Smith wrote:
> On Wed, 2008-02-06 at 17:34 -0500, Adam Lichtl wrote:
> > Ah- great!  I was also reading up on .SECONDARY with no
> > prerequisites, 
> > but I suppose I should be specific and save just my object files with:
> >
> > .PRECIOUS: %.o
>
> Note that all you HAVE to do is mention the file you want to preserve
> SOMEWHERE in the makefile, as a target _or_ prerequisite.
>
> As soon as you do that, even if that rule is never used for anything,
> the target won't be deleted.
>
> .PRECIOUS is not exactly what you want, I think, because it says too
> much.  Not only will it preserve the target on exit, but it will ALSO
> preserve the target if make is interrupted or whatever.  This can lead
> to incorrect builds, because the target will only be half-created but
> since it exists and has a new timestamp, make won't try to recreate it.
> Depending on the type of target and what you do with it, the failure
> caused by this could be very subtle.
>
> YMMV.