Source Code for Module mvpa.misc.args

 1  # emacs: -*- mode: python; py-indent-offset: 4; indent-tabs-mode: nil -*- 
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 4  # 
 5  #   See COPYING file distributed along with the PyMVPA package for the 
 6  #   copyright and license terms. 
 7  # 
 8  ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ## 
 9  """Helpers for arguments handling.""" 
10   
11  __docformat__ = 'restructuredtext' 
12   
13 -def split_kwargs(kwargs, prefixes=[]): 
14      """Helper to separate kwargs into multiple groups 
15   
16      :Parameters: 
17        prefixes : list of basestrings 
18          Each entry sets a prefix which puts entry with key starting 
19          with it into a separate group. 
20          Group '' corresponds to 'leftovers' 
21   
22      :Output: 
23        dictionary with keys == `prefixes` 
24      """ 
25      if not ('' in prefixes): 
26          prefixes = prefixes + [''] 
27      result = [ [] for i in prefixes ] 
28      for k,v in kwargs.iteritems(): 
29          for i,p in enumerate(prefixes): 
30              if k.startswith(p): 
31                  result[i].append((k.replace(p,'',1), v)) 
32                  break 
33      resultd = dict((p,dict(x)) for p,x in zip(prefixes, result)) 
34      return resultd 
35   
36   
37 -def group_kwargs(prefixes, assign=False, passthrough=False): 
38      """Decorator function to join parts of kwargs together 
39   
40      :Parameters: 
41        prefixes : list of basestrings 
42          Prefixes to split based on. See `split_kwargs` 
43        assign : bool 
44          Flag to assign the obtained arguments to self._<prefix>_kwargs 
45        passthrough : bool 
46          Flag to pass joined arguments as <prefix>_kwargs argument. 
47          Usually it is sufficient to have either assign or passthrough. 
48          If none of those is True, decorator simply filters out mentioned 
49          groups from being passed to the method 
50   
51      Example: if needed to join all args which start with 'slave<underscore>' 
52      together under slave_kwargs parameter 
53      """ 
54      def decorated_method(method): 
55          def do_group_kwargs(self, *args_, **kwargs_): 
56              if '' in prefixes: 
57                  raise ValueError, \ 
58                        "Please don't put empty string ('') into prefixes" 
59              # group as needed 
60              splits = split_kwargs(kwargs_, prefixes) 
61              # adjust resultant kwargs__ 
62              kwargs__ = splits[''] 
63              for prefix in prefixes: 
64                  skwargs = splits[prefix] 
65                  k = '%skwargs' % prefix 
66                  if k in kwargs__: 
67                      # is unprobable but can happen 
68                      raise ValueError, '%s is already given in the arguments' % k 
69                  if passthrough:   kwargs__[k] = skwargs 
70                  if assign: setattr(self, '_%s' % k, skwargs) 
71              return method(self, *args_, **kwargs__) 
72          do_group_kwargs.func_name = method.func_name 
73          return do_group_kwargs 
74   
75      return decorated_method 
76