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#general
Title
# general
c

curved-television-6568

12/09/2021, 7:54 AM
I have a target generator question 🧵
Say I have a
requirements.txt
file. Using the
python_requirements
target I can turn that into a bunch of generated
python_requirement
targets. Now, if I change one of the requirements in
requirements.txt
, is there a way to single out that
python_requirement
target so I don’t have to rebuild everything that depends on any generated target from those requirements, but only the one that was actually changed?
I’m using the
--changed-since
option, and that treats the whole file as a single unit, which is a bit unfortunate (I have another target gen using another kind of input source file)
Hmm… I realise that this is perhaps not really possible, but that I should instead split my input source files into smaller units, and source them with a glob instead…
OK, so a bit of my confusion may come from this fact:
Copy code
$ ./pants dependees mirror/images.txt 
09:30:53.15 [ERROR] 1 Exception encountered:

  ResolveError: No owning targets could be found for the file `mirror/images.txt`.

Please check that there is a BUILD file in the parent directory mirror with a target whose `sources` field includes the file. See <https://www.pantsbuild.org/v2.9/docs/targets> for more information on target definitions.

You may want to run `./pants tailor` to autogenerate your BUILD files. See <https://www.pantsbuild.org/v2.9/docs/create-initial-build-files>.

If you would like to ignore un-owned files, please pass `--owners-not-found-behavior=ignore`.

$ ./pants peek mirror:mirror
[
  {
    "address": "mirror:mirror",
    "target_type": "docker_mirror_images",
    "description": null,
    "overrides": {},
    "source_raw": "images.txt",
    "sources": [
      "mirror/images.txt"
    ],
    "tags": null
  }
]
From what
peek
tells me, my target gen
docker_mirror_images
has
mirror/images.txt
as its sources, so why do I get the unowned file error above.. ?
investigating…
Ah, the generator target itself is excluded… hmm… OK, I think I recall something regarding this from the generator discussions, so I understand it is due to not producing confusing output with
list ::
etc…
So it’s a gotcha that target generators that has input source(s), need to also generate targets for those inputs, and add dependencies to those as needed, then, I guess.. makes kind of sense to be able to control the behaviour here on a per generator basis. (would love some docs on target generators 😁 unless I’ve missed them)
OK - so that solved it.
h

hundreds-father-404

12/13/2021, 7:45 PM
is this using
python_requirements
as provided by Pants? Reminder that is using the old CAOF API rather than target generators
c

curved-television-6568

12/13/2021, 8:34 PM
No it’s a custom generator, so not using CAOF.
Used the
python_requirement
as example, as it has the same semantics from a user perspective.
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