Class Dataset

tests/scripts/test_change_tracking.py:39–60

A virtual dataset: a read-set (union-over-history) + last-run clock.

class Dataset:
    """A virtual dataset: a read-set (union-over-history) + last-run clock."""

    def __init__(self, reads):
        self.reads = reads  # slots its transform reads when it runs
        self.read_slots = []  # discovered union read-set
        self.last_run_clock = 0
        self.runs = 0

    def should_run(self, store):
        # empty read-set -> always run (R7); else run iff an input changed
        return not self.read_slots or store.changed_since(
            self.read_slots, self.last_run_clock
        )

    def run(self, store):
        store.set_capture_target(self.read_slots)
        for s in self.reads:
            store.read(s)
        store.set_capture_target(None)
        self.last_run_clock = store.write_clock
        self.runs += 1


def frame(store, datasets):