Item::apply_dry will not work for cases like the following:
FileDownloadItem downloads a tar file.
TarXItem extracts the file.
Currently TarXApplyFns::apply_dry just returns state_goal.clone() as the "successful state", rather than attempting to read the file, and returning whether the dry run fails or signal that the returned state is inaccurate because the file to extract doesn't exist yet.
We need to decide to settle on one of the following:
Keep the API as is -- item implementors cannot assume params / data are usable. Errors returned from each Item count as an execution failure.
Change the signature to know which values are RealOrExample::Real(T) vs RealOrExample::Example(T), and item implementors choose to read external resources for Real<T> variants.
Change the implementation of ItemWrapper::ensure_prepare to call state_goal_try_exec when it is for a dry run, and only call apply_dry if state_goal managed to be fetched.
Tasks
[ ] Determine the contract, update Item::apply_dry.
[ ] Fix ValueResolutionMode::ApplyDry and peace_data::marker::apply_dry::ApplyDry docs.
Item::apply_drywill not work for cases like the following:FileDownloadItemdownloads a tar file.TarXItemextracts the file.Currently
TarXApplyFns::apply_dryjust returnsstate_goal.clone()as the "successful state", rather than attempting to read the file, and returning whether the dry run fails or signal that the returned state is inaccurate because the file to extract doesn't exist yet.We need to decide to settle on one of the following:
params/dataare usable. Errors returned from eachItemcount as an execution failure.RealOrExample::Real(T)vsRealOrExample::Example(T), and item implementors choose to read external resources forReal<T>variants.ItemWrapper::ensure_prepareto callstate_goal_try_execwhen it is for a dry run, and only callapply_dryifstate_goalmanaged to be fetched.Tasks
Item::apply_dry.ValueResolutionMode::ApplyDryandpeace_data::marker::apply_dry::ApplyDrydocs.*Items.