[Scons-users] Emitters vs. Scanners

[Bill Deegan]

Tom,

Likely DynamicSourceGenerator is overkill for u.

Can you create a small example to demonstrate your problem?

If a->b is entirely predictable, then is there a:

env.MyBuilder('b','a')
env.otherBuilder('c','b')

If SCons doesn't know that b is generated from a, then I can see the issue
you're running into.
lex/yacc do similar and have no issues..

-Bill

On Fri, Mar 11, 2016 at 5:07 PM, Plunket, Tom <
tom.plunket at aristocrat-inc.com> wrote:

> I am struggling with an issue where an intermediate file is getting
> scanned for targets even though it is about to get regenerated.  I’m
> curious if I need to change my Scanner into an Emitter or if there’s
> something else I should be considering?
>
>
>
> The flow is A->B->C, A is the input file which creates B. B is the primary
> source for C but (B) also lists a bunch of other files that need to go into
> C.  filename.a gets processed into filename.b and that, along with the
> results of the scan get bundled up into filename.c. The closest software
> construction analogy would be that A is like a “premake” or “makefile.in”
> file, B would be the makefile and would list the source files to be
> compiled, and C is the executable that results.
>
>
>
> If B exists, it gets scanned during dependency generation by the scanner,
> even if A has changed. This is a problem if B refers to invalid or
> otherwise broken dependencies that have been fixed by the changes to A,
> since I will not be able to build nor clean these items without manually
> deleting B.
>
>
>
> I’m looking at
> https://bitbucket.org/scons/scons/wiki/DynamicSourceGenerator but I’m not
> yet sure that it’ll fix my problem (or maybe it’s overkill) since B exists,
> it just needs to get recreated before getting scanned. (Could/should it be
> considered a deficiency to scan a file that’s scheduled for replacement in
> the first place?)
>
>
>
> Thanks and sorry for the corporate junk that the email gateway sticks on
> the end of this message.
>
>
>
> --
>
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