Add source files

Author: bat67

abc/abc_abc_base.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+#
+# Copyright (c) 2009 Doug Hellmann All rights reserved.
+#
+"""
+"""
+
+#end_pymotw_header
+import abc
+
+
+class PluginBase(abc.ABC):
+
+    @abc.abstractmethod
+    def load(self, input):
+        """Retrieve data from the input source
+        and return an object.
+        """
+
+    @abc.abstractmethod
+    def save(self, output, data):
+        """Save the data object to the output."""
+
+
+class SubclassImplementation(PluginBase):
+
+    def load(self, input):
+        return input.read()
+
+    def save(self, output, data):
+        return output.write(data)
+
+
+if __name__ == '__main__':
+    print('Subclass:', issubclass(SubclassImplementation,
+                                  PluginBase))
+    print('Instance:', isinstance(SubclassImplementation(),
+                                  PluginBase))

abc/abc_abstractproperty.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+#
+# Copyright (c) 2009 Doug Hellmann All rights reserved.
+#
+"""
+"""
+
+#end_pymotw_header
+import abc
+
+
+class Base(abc.ABC):
+
+    @property
+    @abc.abstractmethod
+    def value(self):
+        return 'Should never reach here'
+
+    @property
+    @abc.abstractmethod
+    def constant(self):
+        return 'Should never reach here'
+
+
+class Implementation(Base):
+
+    @property
+    def value(self):
+        return 'concrete property'
+
+    constant = 'set by a class attribute'
+
+
+try:
+    b = Base()
+    print('Base.value:', b.value)
+except Exception as err:
+    print('ERROR:', str(err))
+
+i = Implementation()
+print('Implementation.value   :', i.value)
+print('Implementation.constant:', i.constant)

abc/abc_abstractproperty_rw.py

@@ -0,0 +1,65 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+#
+# Copyright (c) 2009 Doug Hellmann All rights reserved.
+#
+"""
+"""
+
+#end_pymotw_header
+import abc
+
+
+class Base(abc.ABC):
+
+    @property
+    @abc.abstractmethod
+    def value(self):
+        return 'Should never reach here'
+
+    @value.setter
+    @abc.abstractmethod
+    def value(self, new_value):
+        return
+
+
+class PartialImplementation(Base):
+
+    @property
+    def value(self):
+        return 'Read-only'
+
+
+class Implementation(Base):
+
+    _value = 'Default value'
+
+    @property
+    def value(self):
+        return self._value
+
+    @value.setter
+    def value(self, new_value):
+        self._value = new_value
+
+
+try:
+    b = Base()
+    print('Base.value:', b.value)
+except Exception as err:
+    print('ERROR:', str(err))
+
+p = PartialImplementation()
+print('PartialImplementation.value:', p.value)
+
+try:
+    p.value = 'Alteration'
+    print('PartialImplementation.value:', p.value)
+except Exception as err:
+    print('ERROR:', str(err))
+
+i = Implementation()
+print('Implementation.value:', i.value)
+
+i.value = 'New value'
+print('Changed value:', i.value)

abc/abc_base.py

@@ -0,0 +1,23 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+#
+# Copyright (c) 2009 Doug Hellmann All rights reserved.
+#
+"""
+"""
+
+#end_pymotw_header
+import abc
+
+
+class PluginBase(metaclass=abc.ABCMeta):
+
+    @abc.abstractmethod
+    def load(self, input):
+        """Retrieve data from the input source
+        and return an object.
+        """
+
+    @abc.abstractmethod
+    def save(self, output, data):
+        """Save the data object to the output."""

abc/abc_class_static.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+#
+# Copyright (c) 2009 Doug Hellmann All rights reserved.
+#
+"""
+"""
+
+#end_pymotw_header
+import abc
+
+
+class Base(abc.ABC):
+
+    @classmethod
+    @abc.abstractmethod
+    def factory(cls, *args):
+        return cls()
+
+    @staticmethod
+    @abc.abstractmethod
+    def const_behavior():
+        return 'Should never reach here'
+
+
+class Implementation(Base):
+
+    def do_something(self):
+        pass
+
+    @classmethod
+    def factory(cls, *args):
+        obj = cls(*args)
+        obj.do_something()
+        return obj
+
+    @staticmethod
+    def const_behavior():
+        return 'Static behavior differs'
+
+
+try:
+    o = Base.factory()
+    print('Base.value:', o.const_behavior())
+except Exception as err:
+    print('ERROR:', str(err))
+
+i = Implementation.factory()
+print('Implementation.const_behavior :', i.const_behavior())

abc/abc_concrete_method.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+#
+# Copyright (c) 2009 Doug Hellmann All rights reserved.
+#
+"""
+"""
+
+#end_pymotw_header
+import abc
+import io
+
+
+class ABCWithConcreteImplementation(abc.ABC):
+
+    @abc.abstractmethod
+    def retrieve_values(self, input):
+        print('base class reading data')
+        return input.read()
+
+
+class ConcreteOverride(ABCWithConcreteImplementation):
+
+    def retrieve_values(self, input):
+        base_data = super(ConcreteOverride,
+                          self).retrieve_values(input)
+        print('subclass sorting data')
+        response = sorted(base_data.splitlines())
+        return response
+
+
+input = io.StringIO("""line one
+line two
+line three
+""")
+
+reader = ConcreteOverride()
+print(reader.retrieve_values(input))
+print()

abc/abc_find_subclasses.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+#
+# Copyright (c) 2009 Doug Hellmann All rights reserved.
+#
+"""
+"""
+
+#end_pymotw_header
+import abc
+from abc_base import PluginBase
+import abc_subclass
+import abc_register
+
+for sc in PluginBase.__subclasses__():
+    print(sc.__name__)

abc/abc_incomplete.py

@@ -0,0 +1,25 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+#
+# Copyright (c) 2009 Doug Hellmann All rights reserved.
+#
+"""
+"""
+
+#end_pymotw_header
+import abc
+from abc_base import PluginBase
+
+
+@PluginBase.register
+class IncompleteImplementation(PluginBase):
+
+    def save(self, output, data):
+        return output.write(data)
+
+
+if __name__ == '__main__':
+    print('Subclass:', issubclass(IncompleteImplementation,
+                                  PluginBase))
+    print('Instance:', isinstance(IncompleteImplementation(),
+                                  PluginBase))

abc/abc_register.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+#
+# Copyright (c) 2009 Doug Hellmann All rights reserved.
+#
+"""
+"""
+
+#end_pymotw_header
+import abc
+from abc_base import PluginBase
+
+
+class LocalBaseClass:
+    pass
+
+
+@PluginBase.register
+class RegisteredImplementation(LocalBaseClass):
+
+    def load(self, input):
+        return input.read()
+
+    def save(self, output, data):
+        return output.write(data)
+
+
+if __name__ == '__main__':
+    print('Subclass:', issubclass(RegisteredImplementation,
+                                  PluginBase))
+    print('Instance:', isinstance(RegisteredImplementation(),
+                                  PluginBase))

abc/abc_subclass.py

@@ -0,0 +1,27 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+#
+# Copyright (c) 2009 Doug Hellmann All rights reserved.
+#
+"""
+"""
+
+#end_pymotw_header
+import abc
+from abc_base import PluginBase
+
+
+class SubclassImplementation(PluginBase):
+
+    def load(self, input):
+        return input.read()
+
+    def save(self, output, data):
+        return output.write(data)
+
+
+if __name__ == '__main__':
+    print('Subclass:', issubclass(SubclassImplementation,
+                                  PluginBase))
+    print('Instance:', isinstance(SubclassImplementation(),
+                                  PluginBase))

argparse/argparse_FileType.py

@@ -0,0 +1,24 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+#
+# Copyright (c) 2010 Doug Hellmann.  All rights reserved.
+#
+"""
+"""
+
+#end_pymotw_header
+import argparse
+
+parser = argparse.ArgumentParser()
+
+parser.add_argument('-i', metavar='in-file',
+                    type=argparse.FileType('rt'))
+parser.add_argument('-o', metavar='out-file',
+                    type=argparse.FileType('wt'))
+
+try:
+    results = parser.parse_args()
+    print('Input file:', results.i)
+    print('Output file:', results.o)
+except IOError as msg:
+    parser.error(str(msg))