`zope.deprecation` Documentation¶

Contents:

`zope.deprecation` API¶

Deprecating objects inside a module¶

Let’s start with a demonstration of deprecating any name inside a module. To demonstrate the functionality, First, let’s set up an example module containing fixtures we will use:

>>> import os
>>> import tempfile
>>> import zope.deprecation
>>> tmp_d = tempfile.mkdtemp('deprecation')
>>> zope.deprecation.__path__.append(tmp_d)
>>> doctest_ex = '''\
... from . import deprecated
...
... def demo1(): #pragma NO COVER  (used only in doctests)
...     return 1
... deprecated('demo1', 'demo1 is no more.')
...
... def demo2(): #pragma NO COVER  (used only in doctests)
...     return 2
... deprecated('demo2', 'demo2 is no more.')
...
... def demo3(): #pragma NO COVER  (used only in doctests)
...     return 3
... deprecated('demo3', 'demo3 is no more.')
...
... def demo4(): #pragma NO COVER  (used only in doctests)
...     return 4
... def deprecatedemo4(): #pragma NO COVER  (used only in doctests)
...     """Demonstrate that deprecated() also works in a local scope."""
...     deprecated('demo4', 'demo4 is no more.')
... '''
>>> with open(os.path.join(tmp_d, 'doctest_ex.py'), 'w') as f:
...     f.write(doctest_ex)

The first argument to the deprecated() function is a list of names that should be declared deprecated. If the first argument is a string, it is interpreted as one name. The second argument is the reason the particular name has been deprecated. It is good practice to also list the version in which the name will be removed completely.

Let’s now see how the deprecation warnings are displayed.

>>> import warnings
>>> from zope.deprecation import doctest_ex
>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     doctest_ex.demo1()
1
>>> print log[0].category.__name__
DeprecationWarning
>>> print log[0].message
demo1: demo1 is no more.

>>> import zope.deprecation.doctest_ex
>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     zope.deprecation.doctest_ex.demo2()
2
>>> print log[0].message
demo2: demo2 is no more.

You can see that merely importing the affected module or one of its parents does not cause a deprecation warning. Only when we try to access the name in the module, we get a deprecation warning. On the other hand, if we import the name directly, the deprecation warning will be raised immediately.

>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     from zope.deprecation.doctest_ex import demo3
>>> print log[0].message
demo3: demo3 is no more.

Deprecation can also happen inside a function. When we first access demo4, it can be accessed without problems, then we call a function that sets the deprecation message and we get the message upon the next access:

>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     doctest_ex.demo4()
4
>>> len(log)
0
>>> doctest_ex.deprecatedemo4()
>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     doctest_ex.demo4()
4
>>> print log[0].message.message #XXX oddball case: why nested?
demo4: demo4 is no more.

Deprecating methods and properties¶

New let’s see how properties and methods can be deprecated. We are going to use the same function as before, except that this time, we do not pass in names as first argument, but the method or attribute itself. The function then returns a wrapper that sends out a deprecation warning when the attribute or method is accessed.

>>> from zope.deprecation import deprecation
>>> class MyComponent(object):
...     foo = property(lambda self: 1)
...     foo = deprecation.deprecated(foo, 'foo is no more.')
...
...     bar = 2
...
...     def blah(self):
...         return 3
...     blah = deprecation.deprecated(blah, 'blah() is no more.')
...
...     def splat(self):
...         return 4
...
...     @deprecation.deprecate("clap() is no more.")
...     def clap(self):
...         return 5

And here is the result:

>>> my = MyComponent()
>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     my.foo
1
>>> print log[0].message.message # XXX see above
foo is no more.
>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     my.bar
2
>>> len(log)
0
>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     my.blah()
3
>>> print log[0].message.message # XXX see above
blah() is no more.
>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     my.splat()
4
>>> len(log)
0
>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     my.clap()
5
>>> print log[0].message.message # XXX see above
clap() is no more.

Deprecating modules¶

It is also possible to deprecate whole modules. This is useful when creating module aliases for backward compatibility. Let’s imagine, the zope.deprecation module used to be called zope.wanda and we’d like to retain backward compatibility:

>>> import sys
>>> sys.modules['zope.wanda'] = deprecation.deprecated(
...     zope.deprecation, 'A module called Wanda is now zope.deprecation.')

Now we can import wanda, but when accessing things from it, we get our deprecation message as expected:

>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     from zope.wanda import deprecated
>>> print log[0].message.message # XXX see above
A module called Wanda is now zope.deprecation.

Before we move on, we should clean up:

>>> del deprecated
>>> del sys.modules['zope.wanda']

Moving modules¶

When a module is moved, you often want to support importing from the old location for a while, generating a deprecation warning when someone uses the old location. This can be done using the moved function.

To see how this works, we’ll use a helper function to create two fake modules in the zope.deprecation package. First will create a module in the “old” location that used the moved function to indicate the a module on the new location should be used:

>>> import os
>>> created_modules = []
>>> def create_module(modules=(), **kw): #** highlightfail
...     modules = dict(modules)
...     modules.update(kw)
...     for name, src in modules.iteritems():
...         pname = name.split('.')
...         if pname[-1] == '__init__':
...             os.mkdir(os.path.join(tmp_d, *pname[:-1])) #* highlightfail
...             name = '.'.join(pname[:-1])
...         open(os.path.join(tmp_d, *pname)+'.py', 'w').write(src) #* hf
...         created_modules.append(name)
>>> create_module(old_location=
... '''
... import zope.deprecation
... zope.deprecation.moved('zope.deprecation.new_location', 'version 2')
... ''')

and we define the module in the new location:

>>> create_module(new_location=
... '''\
... print "new module imported"
... x = 42
... ''')

Now, if we import the old location, we’ll see the output of importing the old location:

>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     import zope.deprecation.old_location
new module imported
>>> print log[0].message.message
... 
zope.deprecation.old_location has moved to zope.deprecation.new_location.
Import of zope.deprecation.old_location will become unsupported
in version 2
>>> zope.deprecation.old_location.x
42

Moving packages¶

When moving packages, you need to leave placeholders for each module. Let’s look at an example:

>>> create_module({
... 'new_package.__init__': '''\
... print __name__, 'imported'
... x=0
... ''',
... 'new_package.m1': '''\
... print __name__, 'imported'
... x=1
... ''',
... 'new_package.m2': '''\
... print __name__, 'imported'
... def x():
...     pass
... ''',
... 'new_package.m3': '''\
... print __name__, 'imported'
... x=3
... ''',
... 'old_package.__init__': '''\
... import zope.deprecation
... zope.deprecation.moved('zope.deprecation.new_package', 'version 2')
... ''',
... 'old_package.m1': '''\
... import zope.deprecation
... zope.deprecation.moved('zope.deprecation.new_package.m1', 'version 2')
... ''',
... 'old_package.m2': '''\
... import zope.deprecation
... zope.deprecation.moved('zope.deprecation.new_package.m2', 'version 2')
... ''',
... })

Now, if we import the old modules, we’ll get warnings:

>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     import zope.deprecation.old_package
zope.deprecation.new_package imported
>>> print log[0].message
... 
zope.deprecation.old_package has moved to zope.deprecation.new_package.
Import of zope.deprecation.old_package will become unsupported in version 2
>>> zope.deprecation.old_package.x
0

>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     import zope.deprecation.old_package.m1
zope.deprecation.new_package.m1 imported
>>> print log[0].message
... 
zope.deprecation.old_package.m1 has moved to zope.deprecation.new_package.m1.
Import of zope.deprecation.old_package.m1 will become unsupported in
version 2
>>> zope.deprecation.old_package.m1.x
1

>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     import zope.deprecation.old_package.m2
zope.deprecation.new_package.m2 imported
>>> print log[0].message
... 
zope.deprecation.old_package.m2 has moved to zope.deprecation.new_package.m2.
Import of zope.deprecation.old_package.m2 will become unsupported in
version 2
>>> zope.deprecation.old_package.m2.x is zope.deprecation.new_package.m2.x
True

>>> (zope.deprecation.old_package.m2.x.func_globals
...  is zope.deprecation.new_package.m2.__dict__)
True

>>> zope.deprecation.old_package.m2.x.__module__
'zope.deprecation.new_package.m2'

We’ll get an error if we try to import m3, because we didn’t create a placeholder for it:

>>> import  zope.deprecation.old_package.m3
Traceback (most recent call last):
...
ImportError: No module named m3

Before we move on, let’s clean up the temporary modules / packages:

>>> zope.deprecation.__path__.remove(tmp_d)
>>> import shutil
>>> shutil.rmtree(tmp_d)

Temporarily turning off deprecation warnings¶

In some cases it is desireable to turn off the deprecation warnings for a short time.

To support such a feature, the zope.deprecation package provides a context manager class, zope.deprecation.Suppressor. Code running inside the scope of a Suppressor will not emit deprecation warnings.

>>> from zope.deprecation import Suppressor
>>> class Foo(object):
...     bar = property(lambda self: 1)
...     bar = deprecation.deprecated(bar, 'bar is no more.')
...     blah = property(lambda self: 1)
...     blah = deprecation.deprecated(blah, 'blah is no more.')
>>> foo = Foo()
>>> with Suppressor():
...    foo.blah
1

Note that no warning is emitted when foo.blah is accessed inside the suppressor’s scope.:

The suppressor is implemented in terms of a __show__ object. One can ask for its status by calling it:

>>> from zope.deprecation import __show__
>>> __show__()
True

Inside a suppressor’s scope, that status is always false:

>>> with Suppressor():
...     __show__()
False

>>> with warnings.catch_warnings(record=True) as log:
...     del warnings.filters[:]
...     foo.bar
1
>>> print log[0].message
bar is no more.

If needed, your code can manage the depraction warnings manually using the on() and off() methods of the __show__ object:

>>> __show__.off()
>>> __show__()
False

>>> foo.blah
1

Now, you can also nest several turn-offs, so that calling off() multiple times is meaningful:

>>> __show__.stack
[False]

>>> __show__.off()
>>> __show__.stack
[False, False]

>>> __show__.on()
>>> __show__.stack
[False]
>>> __show__()
False

>>> __show__.on()
>>> __show__.stack
[]
>>> __show__()
True

You can also reset __show__ to True:

>>> __show__.off()
>>> __show__.off()
>>> __show__()
False

>>> __show__.reset()
>>> __show__()
True

Finally, you cannot call on() without having called off() before:

>>> __show__.on()
Traceback (most recent call last):
...
IndexError: pop from empty list

Hacking on `zope.deprecation`¶

Getting the Code¶

The main repository for zope.deprecation is in the Zope Foundation Github repository:

https://github.com/zopefoundation/zope.deprecation

You can get a read-only checkout from there:

$ git clone https://github.com/zopefoundation/zope.deprecation.git

or fork it and get a writeable checkout of your fork:

$ git clone git@github.com/jrandom/zope.deprecation.git

The project also mirrors the trunk from the Github repository as a Bazaar branch on Launchpad:

https://code.launchpad.net/zope.deprecation

You can branch the trunk from there using Bazaar:

$ bzr branch lp:zope.deprecation

Working in a `virtualenv`¶

Installing¶

If you use the virtualenv package to create lightweight Python development environments, you can run the tests using nothing more than the python binary in a virtualenv. First, create a scratch environment:

$ /path/to/virtualenv --no-site-packages /tmp/hack-zope.deprecation

Next, get this package registered as a “development egg” in the environment:

$ /tmp/hack-zope.deprecation/bin/python setup.py develop

Running the tests¶

Run the tests using the build-in setuptools testrunner:

$ /tmp/hack-zope.deprecation/bin/python setup.py test
running test
....................................................
----------------------------------------------------------------------
Ran 52 tests in 0.155s

OK

If you have the nose package installed in the virtualenv, you can use its testrunner too:

$ /tmp/hack-zope.deprecation/bin/easy_install nose
...
$ /tmp/hack-zope.deprecation/bin/python setup.py nosetests
running nosetests
....................................................
----------------------------------------------------------------------
Ran 52 tests in 0.155s

OK

or:

$ /tmp/hack-zope.deprecation/bin/nosetests
....................................................
----------------------------------------------------------------------
Ran 52 tests in 0.155s

OK

If you have the coverage pacakge installed in the virtualenv, you can see how well the tests cover the code:

$ /tmp/hack-zope.deprecation/bin/easy_install nose coverage
...
$ /tmp/hack-zope.deprecation/bin/python setup.py nosetests \
    --with coverage --cover-package=zope.deprecation
running nosetests
....................................................
Name                           Stmts   Miss  Cover   Missing
------------------------------------------------------------
zope.deprecation                   7      0   100%
zope.deprecation.deprecation     127      0   100%
zope.deprecation.fixture           1      0   100%
------------------------------------------------------------
TOTAL                            135      0   100%
----------------------------------------------------------------------
Ran 52 tests in 0.155s

OK

Building the documentation¶

zope.deprecation uses the nifty Sphinx documentation system for building its docs. Using the same virtualenv you set up to run the tests, you can build the docs:

$ /tmp/hack-zope.deprecation/bin/easy_install Sphinx
...
$ bin/sphinx-build -b html -d docs/_build/doctrees docs docs/_build/html
...
build succeeded.

You can also test the code snippets in the documentation:

$ bin/sphinx-build -b doctest -d docs/_build/doctrees docs docs/_build/doctest
...

Doctest summary
===============
   89 tests
    0 failures in tests
    0 failures in setup code
build succeeded.
Testing of doctests in the sources finished, look at the  \
    results in _build/doctest/output.txt.

Using `zc.buildout`¶

Setting up the buildout¶

zope.deprecation ships with its own buildout.cfg file and bootstrap.py for setting up a development buildout:

$ /path/to/python2.6 bootstrap.py
...
Generated script '.../bin/buildout'
$ bin/buildout
Develop: '/home/jrandom/projects/Zope/BTK/deprecation/.'
...
Generated script '.../bin/sphinx-quickstart'.
Generated script '.../bin/sphinx-build'.

Running the tests using¶

Run the tests:

$ bin/test --all
Running zope.testing.testrunner.layer.UnitTests tests:
  Set up zope.testing.testrunner.layer.UnitTests in 0.000 seconds.
  Ran 52 tests with 0 failures and 0 errors in 0.366 seconds.
Tearing down left over layers:
  Tear down zope.testing.testrunner.layer.UnitTests in 0.000 seconds.

Using `tox`¶

Running Tests on Multiple Python Versions¶

tox is a Python-based test automation tool designed to run tests against multiple Python versions. It creates a virtualenv for each configured version, installs the current package and configured dependencies into each virtualenv, and then runs the configured commands.

zope.deprecation configures the following tox environments via its tox.ini file:

The py26, py27, py33, py34, and pypy environments builds a virtualenv with pypy, installs zope.deprecation and dependencies, and runs the tests via python setup.py test -q.
The coverage environment builds a virtualenv with python2.6, installs zope.deprecation, installs nose and coverage, and runs nosetests with statement coverage.
The docs environment builds a virtualenv with python2.6, installs zope.deprecation, installs Sphinx and dependencies, and then builds the docs and exercises the doctest snippets.

This example requires that you have a working python2.6 on your path, as well as installing tox:

$ tox -e py26
GLOB sdist-make: .../zope.interface/setup.py
py26 sdist-reinst: .../zope.interface/.tox/dist/zope.interface-4.0.2dev.zip
py26 runtests: commands[0]
..........
----------------------------------------------------------------------
Ran 52 tests in 0.155s

OK
___________________________________ summary ____________________________________
py26: commands succeeded
congratulations :)

Running tox with no arguments runs all the configured environments, including building the docs and testing their snippets:

$ tox
GLOB sdist-make: .../zope.interface/setup.py
py26 sdist-reinst: .../zope.interface/.tox/dist/zope.interface-4.0.2dev.zip
py26 runtests: commands[0]
...
Doctest summary
===============
  89 tests
   0 failures in tests
   0 failures in setup code
   0 failures in cleanup code
build succeeded.
___________________________________ summary ____________________________________
py26: commands succeeded
py27: commands succeeded
py32: commands succeeded
pypy: commands succeeded
coverage: commands succeeded
docs: commands succeeded
congratulations :)

Contributing to `zope.deprecation`¶

Submitting a Bug Report¶

zope.deprecation tracks its bugs on Github:

https://github.com/zopefoundation/zope.deprecation/issues

Please submit bug reports and feature requests there.

zope.deprecation Documentation¶

zope.deprecation API¶