[Scons-users] Emitters vs. Scanners

[Viktor Dick]

On 12.03.2016 03:13, Plunket, Tom wrote:
> Print statements in the scanner (“Scanning blahblah.xml”) print
> before the Scene command string (“Exporting blahblah.aep to
> blahblah.xml”).

I guess that's because SCons works in two steps. First, the whole
dependency graph is created (which calls scanners as necessary). Then,
nodes are built. If it is not predictable which sources B will list
additionally until it is created from A, good luck with that. We had a
long discussion on this list a while ago how to create a list of object
files to be linked together in C/C++ projects that follow some
nomenclature for naming of .cpp and .h files. I also tried to create
something like "If you want to create this executable, this intermediate
file is needed. Once the intermediate file is up to date, read it and
you might find further dependencies.", but I was unable to do that with
SCons. My solution was to do the complete first step inside the
SConstruct file, i.e. each time SCons is called I rebuild a database of
"if you want to create this executable, you need to link the object
files from these source files". By using python threads, it is
acceptably fast.

- Viktor

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