Indentation context manager

indent.py

import sys
import functools
import contextlib


@contextlib.contextmanager
def indented_output(indent=4, space=chr(32)):
    """ Precede each carriage return with some quantity of spaces.

        While nesting `indented_output` contexts, be prepared
        that if a line does not begin with a line feed character,
        it shall print with unchanged indentation.
        To keep the indentation as expected,
        print last line feed character of a parent block
        in the beginning of a child block.
    """
    try:
        original_stderr_write = sys.stderr.write
        original_stdout_write = sys.stdout.write

        def write_indented(write_call, data):
            write_call.__call__(
                data.replace('\n', '\n' + (space * indent)))

        sys.stderr.write = functools.partial(
            write_indented, original_stderr_write)
        sys.stdout.write = functools.partial(
            write_indented, original_stdout_write)

        yield
    finally:
        sys.stderr.write = original_stderr_write
        sys.stdout.write = original_stdout_write