cmk/utils/plugin_registry.py

   1 #!/usr/bin/python
   2 # -*- encoding: utf-8; py-indent-offset: 4 -*-
   3 # +------------------------------------------------------------------+
   4 # |             ____ _               _        __  __ _  __           |
   5 # |            / ___| |__   ___  ___| | __   |  \/  | |/ /           |
   6 # |           | |   | '_ \ / _ \/ __| |/ /   | |\/| | ' /            |
   7 # |           | |___| | | |  __/ (__|   <    | |  | | . \            |
   8 # |            \____|_| |_|\___|\___|_|\_\___|_|  |_|_|\_\           |
   9 # |                                                                  |
  10 # | Copyright Mathias Kettner 2014             mk@mathias-kettner.de |
  11 # +------------------------------------------------------------------+
  12 #
  13 # This file is part of Check_MK.
  14 # The official homepage is at http://mathias-kettner.de/check_mk.
  15 #
  16 # check_mk is free software;  you can redistribute it and/or modify it
  17 # under the  terms of the  GNU General Public License  as published by
  18 # the Free Software Foundation in version 2.  check_mk is  distributed
  19 # in the hope that it will be useful, but WITHOUT ANY WARRANTY;  with-
  20 # out even the implied warranty of  MERCHANTABILITY  or  FITNESS FOR A
  21 # PARTICULAR PURPOSE. See the  GNU General Public License for more de-
  22 # tails. You should have  received  a copy of the  GNU  General Public
  23 # License along with GNU Make; see the file  COPYING.  If  not,  write
  24 # to the Free Software Foundation, Inc., 51 Franklin St,  Fifth Floor,
  25 # Boston, MA 02110-1301 USA.
  26
  27 import abc
  28
  29 # TODO: Refactor all plugins to one way of telling the registry it's name.
  30 #       for example let all use a static/class method .name().
  31 #       We could standardize this by making all plugin classes inherit
  32 #       from a plugin base class instead of "object".
  33
  34 # TODO: Decide which base class to implement
  35 # (https://docs.python.org/2/library/collections.html) and cleanup
  36
  37
  38 class ClassRegistry(object):
  39     """The management object for all available plugins of a component.
  40
  41     The snapins are loaded by importing cmk.gui.plugins.[component]. These plugins
  42     contain subclasses of the cmk.gui.plugins.PluginBase (e.g. SidebarSnpain) class.
  43
  44     Entries are registered with this registry using register(), typically via decoration.
  45
  46     """
  47     __metaclass__ = abc.ABCMeta
  48
  49     def __init__(self):
  50         super(ClassRegistry, self).__init__()
  51         self._entries = {}
  52
  53     # TODO: Make staticmethod (But abc.abstractstaticmethod not available. How to make this possible?)
  54     @abc.abstractmethod
  55     def plugin_base_class(self):
  56         raise NotImplementedError()
  57
  58     @abc.abstractmethod
  59     def plugin_name(self, plugin_class):
  60         raise NotImplementedError()
  61
  62     def registration_hook(self, plugin_class):
  63         pass
  64
  65     def register(self, plugin_class):
  66         """Register a class with the registry, can be used as a decorator"""
  67         if not issubclass(plugin_class, self.plugin_base_class()):
  68             raise TypeError('%s is not a subclass of %s' % (plugin_class.__name__,
  69                                                             self.plugin_base_class().__name__))
  70         self.registration_hook(plugin_class)
  71         self._entries[self.plugin_name(plugin_class)] = plugin_class
  72         return plugin_class
  73
  74     def __contains__(self, text):
  75         return text in self._entries
  76
  77     def __delitem__(self, key):
  78         del self._entries[key]
  79
  80     def __getitem__(self, key):
  81         return self._entries[key]
  82
  83     def __len__(self):
  84         return len(self._entries)
  85
  86     def values(self):
  87         return self._entries.values()
  88
  89     def items(self):
  90         return self._entries.items()
  91
  92     def keys(self):
  93         return self._entries.keys()
  94
  95     def get(self, key, deflt=None):
  96         return self._entries.get(key, deflt)