Class HistoryManager

IPython/core/history.py:606–1100

A class to organize all history-related functionality in one place.

class HistoryManager(HistoryAccessor):
    """A class to organize all history-related functionality in one place."""

    # Public interface

    # An instance of the IPython shell we are attached to
    shell = Instance(
        "IPython.core.interactiveshell.InteractiveShellABC", allow_none=False
    )
    # Lists to hold processed and raw history. These start with a blank entry
    # so that we can index them starting from 1
    input_hist_parsed = List([""])
    input_hist_raw = List([""])
    # A list of directories visited during session
    dir_hist: List = List()

    @default("dir_hist")
    def _dir_hist_default(self) -> list[Path]:
        try:
            return [Path.cwd()]
        except OSError:
            return []

    # A dict of output history, keyed with ints from the shell's
    # execution count.
    output_hist = Dict()
    # The text/plain repr of outputs.
    output_hist_reprs: typing.Dict[int, str] = Dict()  # type: ignore [assignment]
    # Maps execution_count to MIME bundles
    outputs: typing.Dict[int, typing.List[HistoryOutput]] = defaultdict(list)
    # Maps execution_count to exception tracebacks
    exceptions: typing.Dict[int, typing.Dict[str, Any]] = Dict()  # type: ignore [assignment]

    # The number of the current session in the history database
    session_number: int = Integer()  # type: ignore [assignment]

    db_log_output = Bool(
        False, help="Should the history database include output? (default: no)"
    ).tag(config=True)
    db_cache_size = Integer(
        0,
        help="Write to database every x commands (higher values save disk access & power).\n"
        "Values of 1 or less effectively disable caching.",
    ).tag(config=True)
    # The input and output caches
    db_input_cache: List[tuple[int, str, str]] = List()
    db_output_cache: List[tuple[int, str]] = List()

    # History saving in separate thread
    save_thread = Instance("IPython.core.history.HistorySavingThread", allow_none=True)

    @property
    def save_flag(self) -> threading.Event | None:
        if self.save_thread is not None:
            return self.save_thread.save_flag
        return None

    # Private interface