Source Code for Module SCons.Variables.BoolVariable'

 1  """engine.SCons.Variables.BoolVariable 
 2   
 3  This file defines the option type for SCons implementing true/false values. 
 4   
 5  Usage example: 
 6   
 7    opts = Variables() 
 8    opts.Add(BoolVariable('embedded', 'build for an embedded system', 0)) 
 9    ... 
10    if env['embedded'] == 1: 
11      ... 
12  """ 
13   
14  # 
15  # Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 The SCons Foundation 
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35  # 
36   
37  __revision__ = "src/engine/SCons/Variables/BoolVariable.py 5023 2010/06/14 22:05:46 scons" 
38   
39  __all__ = ['BoolVariable',] 
40   
41  import SCons.Errors 
42   
43  __true_strings  = ('y', 'yes', 'true', 't', '1', 'on' , 'all' ) 
44  __false_strings = ('n', 'no', 'false', 'f', '0', 'off', 'none') 
45   
46   
47 -def _text2bool(val): 
48      """ 
49      Converts strings to True/False depending on the 'truth' expressed by 
50      the string. If the string can't be converted, the original value 
51      will be returned. 
52   
53      See '__true_strings' and '__false_strings' for values considered 
54      'true' or 'false respectivly. 
55   
56      This is usable as 'converter' for SCons' Variables. 
57      """ 
58      lval = val.lower() 
59      if lval in __true_strings: return True 
60      if lval in __false_strings: return False 
61      raise ValueError("Invalid value for boolean option: %s" % val) 
62   
63   
64 -def _validator(key, val, env): 
65      """ 
66      Validates the given value to be either '0' or '1'. 
67       
68      This is usable as 'validator' for SCons' Variables. 
69      """ 
70      if not env[key] in (True, False): 
71          raise SCons.Errors.UserError( 
72              'Invalid value for boolean option %s: %s' % (key, env[key])) 
73   
74   
75 -def BoolVariable(key, help, default): 
76      """ 
77      The input parameters describe a boolen option, thus they are 
78      returned with the correct converter and validator appended. The 
79      'help' text will by appended by '(yes|no) to show the valid 
80      valued. The result is usable for input to opts.Add(). 
81      """ 
82      return (key, '%s (yes|no)' % help, default, 
83              _validator, _text2bool) 
84   
85  # Local Variables: 
86  # tab-width:4 
87  # indent-tabs-mode:nil 
88  # End: 
89  # vim: set expandtab tabstop=4 shiftwidth=4: 
90