[OE-core] diff between defining a "no-op" task and using [noexec]?

[Robert P. J. Day]

On Fri, 18 Oct 2013, Richard Purdie wrote:

> On Thu, 2013-10-17 at 08:07 -0400, Robert P. J. Day wrote:
> >   using a concrete example, there's this from oe core's
> > linux-dummy.bb:
> >
> > do_configure() {
> >         :
> > }
> >
> > do_compile () {
> >         :
> > }
> >
> > do_install() {
> >         :
> > }
> >
> >   what is the difference between the above and writing:
> >
> > do_configure[noexec] = "1"
> > do_compile[noexec] = "1"
> > do_install[noexec] = "1"
> >
> >   *is* there a difference? if so, does it have to do with the
> > processing of other flags for that task?
> >
> >   i can see that, technically, the first variation still defines a
> > task to be run, while the second specifies that the task *not* be run,
> > so i can appreciate that those two operations have different results.
>
> The difference is just that, with the first case bitbake will run
> the task, it will do nothing. In the second case, bitbake will not
> bother running it at all.

  i figured as much, but is there any important (pragmatic)
distinction between the two if one simply wants to nullify an existing
task?

  if there's a defined task dependency of some kind, i can certainly
see how having a defined task consisting of a no-op would behave
differently from specifying to not run that task at all, in terms of
subsequent dependencies. does that distinction come into play
anywhere? is there an example in the OE source that recognizes this?

  and WRT to how developers should code, is one of these approaches
considered better than the other? i've seen both approaches used in
recipe files, and i'm wondering simply about coding style. thanks.

rday

-- 

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

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