Add local cliapp module

Add a copy of the specific version of the cliapp module required by morph, a
known version of which can't otherwise be guaranteed to be available on
general Linux systems, or via PyPi. Including the module directly allows for
continued development in line with morph, until a time when it may become
desirable to move away from dependence on this module.

With a local copy of cliapp added to morph, it has been shown that morph is
capable of building Baserock images without depending on an existing Baserock
system.

Change-Id: Iab1f7037c7afff054a2404c0552d9b5e4d2d141f

1 files changed, 125 insertions, 0 deletions

diff --git a/cliapp/plugin.py b/cliapp/plugin.py
new file mode 100644
index 00000000..c6ea66fe
--- /dev/null
+++ b/cliapp/plugin.py
@@ -0,0 +1,125 @@
+# Copyright (C) 2009-2012  Lars Wirzenius
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+
+'''A generic plugin manager.
+
+The plugin manager finds files with plugins and loads them. It looks
+for plugins in a number of locations specified by the caller. To add
+a plugin to be loaded, it is enough to put it in one of the locations,
+and name it *_plugin.py. (The naming convention is to allow having
+other modules as well, such as unit tests, in the same locations.)
+
+'''
+
+
+import imp
+import inspect
+import os
+
+
+class Plugin(object):
+
+    '''Base class for plugins.
+
+    A plugin MUST NOT have any side effects when it is instantiated.
+    This is necessary so that it can be safely loaded by unit tests,
+    and so that a user interface can allow the user to disable it,
+    even if it is installed, with no ill effects. Any side effects
+    that would normally happen should occur in the enable() method,
+    and be undone by the disable() method. These methods must be
+    callable any number of times.
+
+    The subclass MAY define the following attributes:
+
+    * name
+    * description
+    * version
+    * required_application_version
+
+    name is the user-visible identifier for the plugin. It defaults
+    to the plugin's classname.
+
+    description is the user-visible description of the plugin. It may
+    be arbitrarily long, and can use pango markup language. Defaults
+    to the empty string.
+
+    version is the plugin version. Defaults to '0.0.0'. It MUST be a
+    sequence of integers separated by periods. If several plugins with
+    the same name are found, the newest version is used. Versions are
+    compared integer by integer, starting with the first one, and a
+    missing integer treated as a zero. If two plugins have the same
+    version, either might be used.
+
+    required_application_version gives the version of the minimal
+    application version the plugin is written for. The first integer
+    must match exactly: if the application is version 2.3.4, the
+    plugin's required_application_version must be at least 2 and
+    at most 2.3.4 to be loaded. Defaults to 0.
+
+    '''
+
+    @property
+    def name(self):
+        return self.__class__.__name__
+
+    @property
+    def description(self):
+        return ''
+
+    @property
+    def version(self):
+        return '0.0.0'
+
+    @property
+    def required_application_version(self):
+        return '0.0.0'
+
+    def setup(self):
+        '''Setup plugin.
+
+        This is called at plugin load time. It should not yet enable the
+        plugin (the ``enable`` method does that), but it might do things
+        like add itself into a hook that adds command line arguments
+        to the application.
+
+        '''
+
+    def enable_wrapper(self):
+        '''Enable plugin.
+
+        The plugin manager will call this method, which then calls the
+        enable method. Plugins should implement the enable method.
+        The wrapper method is there to allow an application to provide
+        an extended base class that does some application specific
+        magic when plugins are enabled or disabled.
+
+        '''
+
+        self.enable()
+
+    def disable_wrapper(self):
+        '''Corresponds to enable_wrapper, but for disabling a plugin.'''
+        self.disable()
+
+    def enable(self):
+        '''Enable the plugin.'''
+        raise NotImplemented()
+
+    def disable(self):
+        '''Disable the plugin.'''
+        raise NotImplemented()
+