threadctxt.py

from contextlib import contextmanager
import threading

class _Local(threading.local):
    def __init__(self):
        self.ctxt = {}
        
_data = _Local()

@contextmanager
def setctxt(**kwargs):
    """
    Context manager that sets some keys/values for the duration
    of the block and then unsets them when it is finished.
    
        with setctxt(foo='abc', bar='123'):
            do_code()
    """
    saved = _data.ctxt.copy()
    _data.ctxt.update(kwargs)
    try:
        yield
    finally:
        _data.ctxt = saved

def getctxt(key, default=None):
  """
  Gets the context value by key, or None if it was not set.
  
      value = getctxt('foo')
  """
  return _data.ctxt.get(key, default)

def hasctxt(key):
  """ Returns true if the context has a value set (even if it is None). """
  return key in _data.ctxt