python_warnings_module_deprecation_warning_quickstart.py

1import warnings
2
3def old_function():
4    # DeprecationWarning is ignored by default in Python unless triggered 
5    # directly by code in __main__ or enabled via command line/code.
6    warnings.warn(
7        "old_function() is deprecated and will be removed in a future version. Use new_function() instead.",
8        category=DeprecationWarning,
9        stacklevel=2
10    )
11    return "This is the old function."
12
13def new_function():
14    return "This is the new function."
15
16if __name__ == "__main__":
17    # Force the display of DeprecationWarnings which are normally suppressed
18    warnings.simplefilter('always', DeprecationWarning)
19    
20    print(old_function())