Source Code for Module kenozooid.component

  1  # 
  2  # Kenozooid - dive planning and analysis toolbox. 
  3  # 
  4  # Copyright (C) 2009-2019 by Artur Wroblewski <wrobell@riseup.net> 
  5  # 
  6  # This program is free software: you can redistribute it and/or modify 
  7  # it under the terms of the GNU General Public License as published by 
  8  # the Free Software Foundation, either version 3 of the License, or 
  9  # (at your option) any later version. 
 10  # 
 11  # This program is distributed in the hope that it will be useful, 
 12  # but WITHOUT ANY WARRANTY; without even the implied warranty of 
 13  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 14  # GNU General Public License for more details. 
 15  # 
 16  # You should have received a copy of the GNU General Public License 
 17  # along with this program.  If not, see <http://www.gnu.org/licenses/>. 
 18  # 
 19   
 20  """ 
 21  Simple component interface injection and component repository querying 
 22  mechanism. 
 23  """ 
 24   
 25  import itertools 
 26  ichain = itertools.chain.from_iterable 
 27  import logging 
 28   
 29  log = logging.getLogger('kenozooid.component') 
 30   
 31  # component registry 
 32  _registry = {} 
 33   
 34 -def inject(iface, **params): 
 35      """ 
 36      Class decorator to declare interface implementation. 
 37   
 38      Injection parameters can be used to query for classes implementing an 
 39      interface and having appropriate values. 
 40   
 41      :Parameters: 
 42       iface 
 43          Interface to inject. 
 44       params 
 45          Injection parameters. 
 46      """ 
 47      def f(cls): 
 48          log.debug('inject interface %s for class %s with params %s' \ 
 49                  % (iface.__name__, cls.__name__, params)) 
 50   
 51          if iface not in _registry: 
 52              _registry[iface] = [] 
 53          _registry[iface].append((cls, params)) 
 54   
 55          return cls 
 56   
 57      return f 
 58   
 59   
 60 -def _applies(p1, p2): 
 61      """ 
 62      Check if values stored in two dictionaries are equal for all keys 
 63      stored in first dictionary. 
 64   
 65      :Parameters: 
 66       p1 
 67          First dictionary. 
 68       p2 
 69          Second dictionary. 
 70      """ 
 71      keys = set(p2.keys()) 
 72      return all(k in keys and p1[k] == p2[k] for k in p1.keys()) 
 73   
 74   
 75 -def query(iface=None, **params): 
 76      """ 
 77      Look for class implementing specified interface. 
 78      """ 
 79      if iface is None: 
 80          data = ichain(_registry.values()) 
 81      elif iface in _registry: 
 82          data = _registry[iface] 
 83      else: 
 84          data = () 
 85   
 86      return (cls for cls, p in data if _applies(params, p)) 
 87   
 88   
 89 -def params(cls): 
 90      """ 
 91      Get interface injection parameters for component realized with 
 92      specified class. 
 93   
 94      :Parameters: 
 95       cls 
 96          Class realizing component. 
 97      """ 
 98      for c, p in ichain(_registry.values()): 
 99          if c == cls: 
100              return p 
101   
102   
103  # vim: sw=4:et:ai 
104