More convenient context manager for mmap.mmap

memorymapped.py

"""More convenient context manager for mmap.mmap."""

from collections.abc import Iterator
import contextlib
import mmap
import os


@contextlib.contextmanager
def memorymapped_compat(path: os.PathLike | str) -> Iterator[mmap.mmap]:
    """Return a block context with `path` as memory-mapped file."""
    f = open(path, 'rb')
    try:
        m = mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ)
        try:
            yield m
        finally:
            m.close()
    finally:
        f.close()


@contextlib.contextmanager
def memorymapped(path: os.PathLike | str)-> Iterator[mmap.mmap]:
    """Return a block context with `path` as memory-mapped file."""
    access = mmap.ACCESS_READ
    with open(path, 'rb') as f, mmap.mmap(f.fileno(), 0, access=access) as m:
        yield m


if __name__ == '__main__':
    for func in(memorymapped_compat, memorymapped):
        print(func)
        with func('memorymapped.py') as data:
            print(data[250:307])
        print()