Re: [RFC PATCH v3 5/9] trace-cmd: Move libparsevent *.c files in lib/pevent

[Vladislav Valtchev <vladislav.valtchev@gmail.com>]

On Wed, 2017-12-13 at 10:49 -0500, Steven Rostedt wrote:
> I didn't mean the DEFAULT_TARGET when I said "the above", I was just
> referring to OBJS, which I now see that could be somewhat ambiguous in
> what I meant.
> 
> > While OBJS = is a "coding style" thing in order to have all the
> > objects added with +=, one per line.
> 
> I like the "+=" but do we really need to initialize it to nothing
> first? Doesn't make work if you just simply remove the "OBJS =" blank
> line, and a "OBJS += blah" will make OBJS equal to "blah" if OBJS
> doesn't exist yet.
> 

OK, by just using OBJS += ... works.
But: it is a dangerous in case the parent file had an OBJS variable exported:
in that case, the variable won't be cleared first and we'll end up with the wrong
objects.

I copied the practice of using OBJS = and later OBJS += ... from the original Makefile:

PLUGIN_OBJS =
PLUGIN_OBJS += plugin_jbd2.o
PLUGIN_OBJS += plugin_hrtimer.o
PLUGIN_OBJS += plugin_kmem.o
PLUGIN_OBJS += plugin_kvm.o
PLUGIN_OBJS += plugin_mac80211.o
PLUGIN_OBJS += plugin_sched_switch.o
PLUGIN_OBJS += plugin_function.o
PLUGIN_OBJS += plugin_xen.o
PLUGIN_OBJS += plugin_scsi.o
PLUGIN_OBJS += plugin_cfg80211.o
PLUGIN_OBJS += plugin_blk.o
PLUGIN_OBJS += plugin_tlb.o 

Would you like the empty assignment to be removed also from there?

Vlad