"""

A decorator to mark functions as deprecated.

When the function is called, a DeprecationWarning is emitted.

Compatible with Python 2.7+ and Python 3.x.

"""

import functools

import warnings

def deprecated(reason=None):

"""

Decorator to mark functions as deprecated.

Emits a DeprecationWarning when the function is called.

Args:

reason (str, optional): Reason for deprecation. Defaults to None.

Usage:

@deprecated("Use another_function instead.")

def old_function(...):

...

"""

def decorator(func):

message = "Call to deprecated function '{}'.{}".format(

func.__name__,

" " + reason if reason else ""

)

@functools.wraps(func)

def wrapped(*args, **kwargs):

warnings.simplefilter('always', DeprecationWarning) # show warning every time

try:

warnings.warn(

message,

category=DeprecationWarning,

stacklevel=2

)

return func(*args, **kwargs)

finally:

warnings.simplefilter('default', DeprecationWarning) # reset filter

return wrapped

# Support both @deprecated and @deprecated("reason")

if callable(reason):

# Used as @deprecated without arguments

func = reason

reason = None

return decorator(func)

else:

return decorator