How Do I Get Warnings.warn To Issue A Warning And Not Ignore The Line?

I'm trying to raise a DeprecationWarning, with a code snippet based on the example shown in the docs. http://docs.python.org/2/library/warnings.html#warnings.warn Official def depr

Solution 1:

From the docs:

By default, Python installs several warning filters, which can be overridden by the command-line options passed to -W and calls to filterwarnings().

• DeprecationWarning and PendingDeprecationWarning, and ImportWarning are ignored.
• BytesWarning is ignored unless the -b option is given once or twice; in this case this warning is either printed (-b) or turned into an exception (-bb).

By default, DeprecationWarning is ignored. You can change the filters using the following:

warnings.simplefilter('always', DeprecationWarning)

Now your warnings should be printed:

>>>import warnings>>>warnings.simplefilter('always', DeprecationWarning)>>>warnings.warn('test', DeprecationWarning)
/home/guest/.env/bin/ipython:1: DeprecationWarning: test
  #!/home/guest/.env/bin/python

Solution 2:

The warnings module implements filtering of warnings based on certain conditions. You can show the default filters by printing warnings.filters:

$ python -c "import warnings; print(warnings.filters)"
[('ignore', None, <type'exceptions.DeprecationWarning'>, None, 0),
 ('ignore', None, <type'exceptions.PendingDeprecationWarning'>, None, 0),
 ('ignore', None, <type'exceptions.ImportWarning'>, None, 0),
 ('ignore', None, <type'exceptions.BytesWarning'>, None, 0)]

As you can see, DeprecationWarning is ignored by default. You can use the functions in the warnings module and the -W command-line option to Python to configure the filters -- see the documentation for details.

Example:

$ python -Wall
Python 2.7.3 (default, Sep 262013, 20:03:06) 
[GCC 4.6.3] on linux2
Type"help", "copyright", "credits"or"license"for more information.
>>> import warnings
>>> warnings.warn("test", DeprecationWarning)
__main__:1: DeprecationWarning: test

Solution 3:

$ python -Wall
Python 2.7.3 (default, Sep 262013, 20:03:06) 
[GCC 4.6.3] on linux2
Type"help", "copyright", "credits"or"license"for more information.
>>> import warnings
>>> warnings.warn("test", DeprecationWarning)
__main__:1: DeprecationWarning: test