settings.py revision 0dcbc4b1714260820fd4b8d6536fbb05e139cc0f 
1#!/usr/bin/python
2
3# Copyright 2011 Google Inc. All Rights Reserved.
4
5
6class Settings(object):
7  """Class representing settings (a set of fields) from an experiment file."""
8
9  def __init__(self, name, settings_type):
10    self.name = name
11    self.settings_type = settings_type
12    self.fields = {}
13    self.parent = None
14
15  def SetParentSettings(self, settings):
16    """Set the parent settings which these settings can inherit from."""
17    self.parent = settings
18
19  def AddField(self, field):
20    name = field.name
21    if name in self.fields:
22      raise Exception("Field %s defined previously." % name)
23    self.fields[name] = field
24
25  def SetField(self, name, value, append=False):
26    if name not in self.fields:
27      raise Exception("'%s' is not a valid field in '%s' settings"
28                      % (name, self.settings_type))
29    if append:
30      self.fields[name].Append(value)
31    else:
32      self.fields[name].Set(value)
33
34  def GetField(self, name):
35    """Get the value of a field with a given name."""
36    if name not in self.fields:
37      raise Exception("Field '%s' not a valid field in '%s' settings." %
38                      (name, self.name))
39    field = self.fields[name]
40    if not field.assigned and field.required:
41      raise Exception("Required field '%s' not defined in '%s' settings." %
42                      (name, self.name))
43    return self.fields[name].Get()
44
45  def Inherit(self):
46    """Inherit any unset values from the parent settings."""
47    for name in self.fields:
48      if (not self.fields[name].assigned and self.parent and
49          name in self.parent.fields and self.parent.fields[name].assigned):
50        self.fields[name].Set(self.parent.GetField(name), parse=False)
51
52  def Override(self, settings):
53    """Override settings with settings from a different object."""
54    for name in settings.fields:
55      if name in self.fields and settings.fields[name].assigned:
56        self.fields[name].Set(settings.GetField(name), parse=False)
57
58  def Validate(self):
59    """Check that all required fields have been set."""
60    for name in self.fields:
61      if not self.fields[name].assigned and self.fields[name].required:
62        raise Exception("Field %s is invalid." % name)
63