Source code for pylib.helper

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""Helper objects.

:Date: 2020-01-01

.. module:: helper
  :platform: *nix, Windows
  :synopsis: Helper objects.

.. moduleauthor:: Daniel Weschke <daniel.weschke@directbox.de>
"""
import os
import time
from contextlib import ContextDecorator

class timeit(ContextDecorator):
  """Meassure time for a function or code block.

  :param description: description for the function or code block
    used for the print-out
  :type description: str

  :Example:

  >>> with timeit('section_test'):
  ...   # code
  section_test took 0.006 ms

  ::

    @timeit('func')
    def func():
      # code

  >>> func()
  func took 0.006 ms
  """
  def __init__(self, description=None):
    self.description = description

  def __enter__(self):
    self.start_time = time.time()
    return self  # to use as: with Timit() as t:

  def __exit__(self, *exc):  #  exc: type, value, traceback
    elapsed_time_ms = (time.time() - self.start_time) * 1000
    print('{:s} took {:.3f} ms'.format(self.description, elapsed_time_ms))
    return False

class cd:
  """Context manager for changing the current working directory

  :param new_path: the directory to change into
  :type new_path: string

  :Example:

  ::

    # enter the directory and run some code:
    with cd("~/tmp"):
      # we are now in ~/tmp
      # code
    # outside the context manager we are back where we started.
  """
  def __init__(self, new_path):
    self.new_path = os.path.expanduser(new_path)

  def __enter__(self):
    self.saved_path = os.getcwd()
    os.chdir(self.new_path)

  def __exit__(self, etype, value, traceback):
    os.chdir(self.saved_path)

def run_file(file_name):
  """Run a file.

  Inside a pythin interpreter it changes to the directory of the
  file and after excuting the file it changes back to the working
  directory before.

  :param file_name: the file to execute
  :type file_name: string
  """
  workdir = os.path.dirname(os.path.abspath(file_name))
  with cd(workdir):
    exec(open(file_name).read())