Baiju Muthukadan's Blog

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   develop = .
   parts =

Adapter pattern
~~~~~~~~~~~~~~~

The adapter concept in Zope Component Architecture and the classic
`adapter pattern` as described in Design Patterns book are very
similar.  But the intent of ZCA adapter usage is more wider than the
`adapter pattern` itself.  The intent of `adapter pattern` is to
convert the interface of a class into another interface clients
expect.  This allows classes work together that couldn't otherwise
because of incompatible interfaces.  But in the `motivation` section
of Design Patterns book, GoF says: "Often the adapter is responsible
for functionality the adapted class doesn't provide".  ZCA adapter has
more focus on adding functionalities than creating a new interface for
an adapted object (adaptee).  ZCA adapter lets adapter classes extend
functionality by adding methods.  (It would be interesting to note
that `Adapter` was known as `Feature` in earlier stage of ZCA
design. ) [#feature]_

The above paragraph has a quote from Gang of Four book, it ends like
this: " ...adapted class doesn't provide".  But in the next sentence I
used "adapted object" instead of "adapted class", because GoF
describes about two variants of adapters based on implementations.
The first one is called `class adapter` and the other one is called
`object adapter`.  A class adapter uses multiple inheritance to adapt
one interface to another, on the other hand an object adapter relies
on object composition.  ZCA adapter is following object adapter
pattern, which use delegation as a mechanism for composition.  GoF's
second principle of object-oriented design goes like this: "Favor
object composition over class inheritance".  For more details about
this subject please read Design Patterns book.

The major attraction of ZCA adapter are the explicit interface for
components and the component registry.  ZCA adapter components are
registered in component registry and looked up by client objects using
interface and name when required.

.. [#feature] Thread discussing renaming of `Feature` to `Adapter`:
   http://mail.zope.org/pipermail/zope3-dev/2001-December/000008.html

 import pkg_resources
 pkg_resources.declare_namespace('zope')

  namespace_packages=['zope']

  namespace_packages=['zope', 'zope.app'],

[buildout]
newest = false
eggs-directory = /mbaiju/eggs
find-links = http://download.zope.org/distribution/

$ buildout --help
...
  -N

    Run in non-newest mode.  This is equivalent to the assignment 
    buildout:newest=false.  With this setting, buildout will not seek
    new distributions if installed distributions satisfy it's
    requirements. 
...

def hello():
    return 'Hello'

import hello
import unittest

class FirstLayer(object):
    pass

class TestHello(unittest.TestCase):
    layer = FirstLayer
    def test_hello(self):
        assert hello.hello() == 'Hello'

def test_suite():
    return unittest.TestSuite((unittest.makeSuite(TestHello)))

import sys
from zope.testing import testrunner
defaults = ['--test-path', '.', '--tests-pattern', 'tests$',]
testrunner.run(defaults)

Running tests.FirstLayer tests:
  Set up tests.FirstLayer in 0.000 seconds.
  Ran 1 tests with 0 failures and 0 errors in 0.000 seconds.
Tearing down left over layers:
  Tear down tests.FirstLayer in 0.000 seconds.

 "Planet GNOME is a window into the world, work and lives of GNOME hackers and
contributors."

 "Planet Ubuntu is a window into the world, work and lives of Ubuntu developers
and contributors."

$ python2.5
Python 2.5 (r25:51908, Sep 27 2006, 12:21:46) 
[GCC 3.3.5 (Debian 1:3.3.5-13)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> any
built-in function any
>>> all
built-in function all
>>> print any.__doc__
any(iterable) -> bool

Return True if bool(x) is True for any x in the iterable.
>>> print all.__doc__
all(iterable) -> bool

Return True if bool(x) is True for all values x in the iterable.
>>> any([1,2])
True
>>> all([1,2])
True
>>> any([1,0])
True
>>> all([1,0])
False

  - a great project
  - a great product
  - a great community

Unit testing
************

Introduction
------------

In this chapter, you will learn more about unit testing.  Zope 3 use `doctest`
based unit testing heavily.  Zope 3 preferes test driven development (TDD).

To explain the idea, consider a use case.  A module is required with a function
which returns 'Good morning, name!'.  The name will be given as argument.
Before writing the real code write the unit test for this.  Infact you will be
writing the real code and it's test cases almost in parallel.  So just create a
file named `example1.py` with just the function definition::

  def goodmorning(name):
      "This returns a good morning message"

See you are not yet wrote the logic yet.  But this is necessary to run tests
successfully with failures!.  Ok, now create a file named `example1.txt`
with test cases, use ReStructuredText format::

  These are test for `example1` module.

  First import the module::

    >>> import example1

  Now call the function `goodmorning` with out any argument::

    >>> example1.goodmorning()
    Traceback (most recent call last):
    ...
    TypeError: goodmorning() takes exactly 1 argument (0 given)

  Now call the function `goodmorning` with one argument::

    >>> example1.goodmorning('Jack')
    'Good morning, Jack!'

See the examples are written like executed from prompt.  You can use your
python prompt and copy paste from there.  Now create another file
`test_example1.py` with this content::

  import unittest
  import doctest

  def test_suite():
      return unittest.TestSuite((
          doctest.DocFileSuite('example1.txt'),
          ))

  if __name__ == '__main__':
      unittest.main(defaultTest='test_suite')

This is just a boilerplate code for running the test.  Now run the test using
`python2.4 test_example1.py` command.
You will get output with following text::

  File "example1.txt", line 16, in example1.txt
  Failed example:
      example1.goodmorning('Jack')
  Expected:
      'Good morning, Jack!'
  Got nothing

Now one test failed, so implement the function now::

  def goodmorning(name):
      "This returns a good morning message"
      return "Good morning, %s!" % name

Now run the test again, it will run without failures.

Now start thinking about other functionalities required for the module.  Before
start coding write about it in text file.  Decide API, write test, write code,
than continue this cycle untill you finish your requirements.

"""sqlite_usage.py: sqlite module usage with examples

First import sqlite::

  >>> import sqlite

Create a temporary directory::

  >>> import tempfile
  >>> tempdir = tempfile.mkdtemp()

Now create a db file::

  >>> import os
  >>> dbfile = os.path.join(tempdir, 'testdb.sdb')

Now connect to db and create a cursor::

  >>> conn = sqlite.connect(dbfile)
  >>> cr = conn.cursor()

Create a table::

  >>> cr.execute("CREATE TABLE first_table (a INT)")

Insert a value and get::

  >>> cr.execute("INSERT INTO first_table (a) values (1)")
  >>> cr.execute("SELECT a FROM first_table")
  >>> cr.fetchall()
  [(1,)]

Test commit and rollback::

  >>> conn.commit()
  >>> cr.execute("DELETE FROM first_table")
  >>> cr.execute("SELECT a FROM first_table")
  >>> cr.fetchall()
  []
  >>> #now rollback and query again
  >>> conn.rollback()
  >>> cr.execute("SELECT a FROM first_table")
  >>> cr.fetchall()
  [(1,)]

Insert more values as parameters::

  >>> cr.execute("CREATE TABLE second_table (a INT, b VARCHAR(20))")
  >>> cr.execute("INSERT INTO second_table (a, b) VALUES (%s, %s)",
  ... (1, 'hi1'))
  >>> cr.execute("SELECT a, b FROM second_table")
  >>> cr.fetchone()
  (1, 'hi1')

Insert more values using executemany::

  >>> cr.executemany("INSERT INTO second_table (a, b) VALUES (%s, %s)",
  ... [(2, 'hi2'), (3, 'hi3')])
  >>> cr.execute("SELECT a, b FROM second_table")
  >>> rst = cr.fetchall()
  >>> (2, 'hi2') in rst
  True
  >>> (3, 'hi3') in rst
  True

Hmm.. there is no rewind::

  >>> cr.rewind
  Traceback (most recent call last):
  ...
  AttributeError: rewind

Views are supported::

  >>> cr.execute("CREATE VIEW first_second_view \
          AS SELECT a.a AS a1, b.a AS a2, b.b \
          FROM first_table AS a LEFT JOIN second_table AS b \
          ON a.a = b.a")
  >>> cr.execute("SELECT a1, a2, b FROM first_second_view")
  >>> cr.fetchone()
  (1, 1, 'hi1')

Cleanup tempdir::

  >>> import shutil
  >>> shutil.rmtree(tempdir)

"""

def _test():
    import doctest
    return doctest.testmod()

if __name__ == '__main__':
    _test()
    pass

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 2. Python advocacy in Kerala
 3. Conduct Python Workshops/conferences
 4. Help developing Python/Python modules
 5. Create a yet another resource site

  import gtk

  class HelloWorld(object):

      def __init__(self):
          self.window = gtk.Window()
          self.button = gtk.Button("Hello")
          self.window.add(self.button)
          self.window.show_all()

      def main(self):
          gtk.main()

  if __name__ == '__main__':
      helloworld = HelloWorld()
      helloworld.main()

  import unittest
  import gtk
  from guitest.gtktest import GtkTestCase

  import hello1

  class TestHelloWorld(GtkTestCase):

      def test_simple_run(self):
          helloworld = hello1.HelloWorld()

      def test_button(self):
          helloworld = hello1.HelloWorld()
          button = helloworld.window.get_child()
          assert type(button) == gtk.Button

      def test_button_text(self):
          helloworld = hello1.HelloWorld()
          button = helloworld.window.get_child()
          assert button.get_label() == "Hello"

  def test_suite():
      suite = unittest.TestSuite()
      suite.addTest(unittest.makeSuite(TestHelloWorld))
      return suite

  if __name__ == '__main__':
      unittest.main()

  import gtk

  class HelloWorld(object):

      def __init__(self):
          self.window = gtk.Window()
          self.button = gtk.Button("Hello")
          self.button.connect("clicked", self.on_button_clicked)
          self.window.add(self.button)
          self.window.show_all()

      def on_button_clicked(self, *args):
          dlg = gtk.MessageDialog(None, 0, gtk.MESSAGE_INFO, gtk.BUTTONS_OK)
          dlg.set_markup("OK")
          ret = dlg.run()
          dlg.destroy()
          return ret

      def main(self):
          gtk.main()

  if __name__ == '__main__':
      helloworld = HelloWorld()
      helloworld.main()

  import unittest
  import gtk
  from guitest.gtktest import GtkTestCase, guistate

  import hello2

  class TestHelloWorld(GtkTestCase):

      def test_button_clicked(self):
          helloworld = hello2.HelloWorld()
          button = helloworld.button
          guistate.dlg_handler = self.handle_hello_clicked
          button.emit("clicked")

      def handle_hello_clicked(self, dlg, *args):
          label = dlg.label
          if label.get_label() == "OK":
              return gtk.RESPONSE_OK
          else:
              self.fail("Label is not 'OK'")

  def test_suite():
      suite = unittest.TestSuite()
      suite.addTest(unittest.makeSuite(TestHelloWorld))
      return suite

  if __name__ == '__main__':
      unittest.main()

  def handle_hello_clicked(self, dlg, *args):
      label = dlg.label
      if label.get_label() == "OK":
          guistate.dlg_handler = self.handle_ok_clicked
          return gtk.RESPONSE_OK
      else:
          self.fail("Label is not 'OK'")


IndentationError: expected an indented block

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Well, actually this is test

any and all built-in functions in Python 2.5