Re: managing dependencies

That said if you have to do this, you're likely doing something wrong.

If you have a custom builder, perhaps you're not adding all the output
files in the emitter or in the emitter call.
SCons can't order dependencies it's not aware of.

-Bill

On Mon, Dec 9, 2019 at 3:26 AM Arvid Rosén <[email protected]> wrote:

> Well,
>
>
>
> In SCons, there is no need to use an extra file for this purpose. You can
> declare dependencies without having files too.
>
>
>
> I mean something like this:
>
>
>
> A = Program(“a.cpp”)
>
> B = Program(“b.cpp”)
>
> C = Program(“c.cpp”)
>
> D = Program(“d.cpp”)
>
>
>
> Depends(C, A)
>
> Depends(D, [A, B])
>
>
>
> Builds of A and B starts immediately. C starts when A is finished. D
> starts when A and B have finished.
>
>
>
> Being a python script, this can be made more general using for loops and
> stuff, and we typically have a variable somewhere to control how many
> products that can be in-flight simultaneously. Btw, this is a typical use
> case of “Requires” rather than “Depends” I guess, but I chose the latter
> for simplicity here.
>
>
>
> Cheers,
>
> Arvid
>
>
>
>
>
>
>
> *From: *daggs <[email protected]>
> *Date: *Monday, 9 December 2019 at 09:04
> *To: *Arvid Rosén <[email protected]>
> *Cc: *SCons users mailing list <[email protected]>
> *Subject: *Re: [Scons-users] managing dependencies
>
>
>
> Greetings,
>
>
>
> something like for all short deps, depend them on a file which I can use
> touch to create?
>
> will the same file for all of them do the job?
>
>
>
> Thank,
>
>
>
> Dagg.
>
>
>
>
>
> *Sent:* Monday, December 09, 2019 at 9:38 AM
> *From:* "Arvid Rosén" <[email protected]>
> *To:* "SCons users mailing list" <[email protected]>
> *Subject:* Re: [Scons-users] managing dependencies
>
> Hi,
>
>
>
> Maybe, but I certainly wouldn’t rely on that.
>
>
>
> We do very massive builds with hundreds of targets in parallel. To avoid
> all targets finishing almost at the same time (competing with each other
> for the same limited resources), we add “fake” dependencies so to schedule
> the builds so that only a couple of targets can be worked on at the same
> time, but still 20 threads or so can be used. This is very easy to do in
> SCons.
>
>
>
> Cheers,
>
> Arvid
>
>
>
> *From: *Scons-users <[email protected]> on behalf of daggs <
> [email protected]>
> *Reply to: *SCons users mailing list <[email protected]>
> *Date: *Monday, 9 December 2019 at 08:06
> *To: *"[email protected]" <[email protected]>
> *Cc: *SCons users mailing list <[email protected]>
> *Subject: *Re: [Scons-users] managing dependencies
>
>
>
> Greetings,
>
>
>
> does the order of dependecy declaration affects the order?
>
>
>
> Dagg.
>
>
>
>
>
> *Sent:* Monday, December 09, 2019 at 1:06 AM
> *From:* "Bill Deegan" <[email protected]>
> *To:* "SCons users mailing list" <[email protected]>
> *Subject:* Re: [Scons-users] managing dependencies
>
> Nope.
>
> You specify the dependencies, SCons figures out the order.
>
> If you need one thing to happen before another then that's a dependency
> you must explicitly list.
>
>
>
> -Bill
>
>
>
> On Sun, Dec 8, 2019 at 4:49 AM daggs <[email protected]> wrote:
>
> Greetings,
>
> I wanted to ask about scons dependencies management, I have a target with
> large number of dependencies, all the dependencies don't have dependencies
> of their own.
> some of the dependencies take more time to generate than the other ones.
> I've noticed that not all the dependencies are handled at the start (I
> have a print at the start of each dependency handling).
> is it possible to instruct scons to give an higher priority to a specific
> dependency?
>
> Thanks,
>
> Dagg.
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