[Scons-users] Non Construction steps in Scons

[Bill Deegan]

I don't see any issues with steps 1-5.
Any set of commands which takes an input file (although other non-file info
can work as well), and produces a target (generally) file can work.
step 1 - perfect fit, input file, output file command (you can use
env.Command() for such)
step 2 - perfect fit, input file + other info (are flags variable, or
fixed), outputs a package file(?) , env.Command()
step 3 - not quite perfect fit, but what I would do is create a output file
with a timestamp after you flash the board, env.Command() can do this, you
can list 2 command, one is flash the board, second is create a timestamp
file.
step 4 - basically same as step 3, though if you don't want SCons to do
dependency management here (building any targets for this), you could just
handle with with python logic in your SConstruct/SConscript to see if that
command is on the command line (
https://scons.org/doc/production/HTML/scons-man.html#v-COMMAND_LINE_TARGETS)
step 5 - does this generate any output files? If not, then also use similar
method as steps 3 & 4.

Curious why you think a generic builder is wrong for step 2?

BTW we do have a discord server if you want to discuss this real time. (
https://discord.gg/pejaFYrD9n)

-Bill



On Sat, May 14, 2022 at 3:48 PM Mats Wichmann <mats at wichmann.us> wrote:

> On 5/14/22 16:18, Duane Ellis wrote:
> > Hi – I am new to scons and I am trying to do something Know how to do in
> > Make
> >
> > Example make rule is like this (I hope this shows up in email
> reasonably)…
> >
> > =============
> >
> > Many-things:   Step1. Step2. Step3 Step4 Step5
> >
> > TARGET=allthings
> >
> > MyApp.ELF:  $(OBJECT_FILES)
> >                 $(LINK_STEP) ….
> >
> > Step1:  MyApp.ELF
> >                 Cmd1
> >
> > Step2:
> >                 Cmd2
> >
> > Step3:
> >                 Cmd3
> >
> > Step4:
> >                 Cmd4
> >
> > Step5:
> >                 Cmd5
> >
> > Allthings:  MyApp.ELF  Step1  Step2 Step3
> >
> > =============
> >
> > In my case, I am working on an embedded platform.
> >
> > I am *NOT* always performing “Construction” – I want to do some other
> > things.
> >
> > Scons can build my app wonderfully – but I can’t get it to do the next
> > several steps – they are not “construction steps” they are procedural
> steps
>
> On the whole (as you're finding out), this isn't really what SCons does
> and so it's sometimes a bit tricky to set these things up.
>
> The first one, however, is well supported;
>
> > Step 1 – I need to post-process my ELF file to create a BIN file in a
> > special way for my board (producing a type of BIN file)
>
> the AddPostAction and AddPreAction methods can help with these needs.
>
> > Step 2 – takes the BIN and ‘packages’ it with special flags unique to
> > this application (A generic builder seems wrong here)
>
> There is some "packaging" support - and usually those are indeed
> builders - but often things under that term can end up quite
> specialized, so that may or may not help you.
>
> > Step 3 – runs a GUI tool in command line mode to “flash” my board, I
> > have to specify on the command line the DEVICE address (either a
> > comport, or a tftp server)
> >
> > Step 4 – runs a command to power cycle the board via a SCPI controlled
> > power supply
> >
> > Step 5 – Launches a Python PyExpect test sequence with a rather
> > complicated command line.
>
> You can create a "phony" target which runs a script to do all these
> things. I use the term phony because normally, to SCons, a target is
> something that is tangible that it can construct.  This can be a bit
> awkward but is certainly doable -  for example, people use this concept
> to run unit tests.
>
> > Other examples are “building both a Library, and a Doxygen package and
> > running the library through a small regression test and “code-formatter”
> > I know how to do that with make… but I don’t see a way of doing that with
>
> There is a contributed doxygen tool in the scons-contrib repository.
> For tests, see the comment above.  For other things, like code
> formatting - consider whether you really want those done as part of the
> scons process, or elsewhere. For example, you can set up pre-commit and
> post-commit hooks in git (conceptually like AddPostAction in SCons), and
> you can set up even more sophisticated tasks of this sort in GitHub and
> Gitlab, should you be using either of those two platforms.  It's just a
> thought, not telling you how to solve your problems.
>
> > What I would like know how to do is:
> >
> >
> >
> > Create a list of arbitrary commands that I can execute in order, If one
> > of those commands fail, I want further progress to stop
> >
> > I would like to say which step depends on the previous step – this is
> > **SPECIFICALLY* not a filename extension thing*
>
> You don't really get to do this: the underlying architectural concept is
> that you tell SCons the relationship between things (e.g. a Builder
> produces targets from the listed sources), it constructs a node graph of
> all those things, and then walks that graph to decide how best to
> complete the build.  If you need very specific ordering of certain
> steps, you need to put them in an external script, or a Python function,
> which applies the constraints you need.
>
> > From the command line, I need to be able to reasonably execute one of
> > the steps at will (ie: like I can do with  “make step4”, or “make
> > allthings”)
>
> Generally speaking you can use Alias to set up targets that are easy to
> invoke from the command line, and aliases are quite flexible so they can
> refer to few or many things, including other Aliases (although there's
> an ordering consideration with chaining aliases).
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