1 """Record of phased-in incompatible language changes.

     2 

     3 Each line is of the form:

     4 

     5     FeatureName = "_Feature(" OptionalRelease "," MandatoryRelease ","

     6                               CompilerFlag ")"

     7 

     8 where, normally, OptionalRelease < MandatoryRelease, and both are 5-tuples

     9 of the same form as sys.version_info:

    10 

    11     (PY_MAJOR_VERSION, # the 2 in 2.1.0a3; an int

    12      PY_MINOR_VERSION, # the 1; an int

    13      PY_MICRO_VERSION, # the 0; an int

    14      PY_RELEASE_LEVEL, # "alpha", "beta", "candidate" or "final"; string

    15      PY_RELEASE_SERIAL # the 3; an int

    16     )

    17 

    18 OptionalRelease records the first release in which

    19 

    20     from __future__ import FeatureName

    21 

    22 was accepted.

    23 

    24 In the case of MandatoryReleases that have not yet occurred,

    25 MandatoryRelease predicts the release in which the feature will become part

    26 of the language.

    27 

    28 Else MandatoryRelease records when the feature became part of the language;

    29 in releases at or after that, modules no longer need

    30 

    31     from __future__ import FeatureName

    32 

    33 to use the feature in question, but may continue to use such imports.

    34 

    35 MandatoryRelease may also be None, meaning that a planned feature got

    36 dropped.

    37 

    38 Instances of class _Feature have two corresponding methods,

    39 .getOptionalRelease() and .getMandatoryRelease().

    40 

    41 CompilerFlag is the (bitfield) flag that should be passed in the fourth

    42 argument to the builtin function compile() to enable the feature in

    43 dynamically compiled code.  This flag is stored in the .compiler_flag

    44 attribute on _Future instances.  These values must match the appropriate

    45 #defines of CO_xxx flags in Include/compile.h.

    46 

    47 No feature line is ever to be deleted from this file.

    48 """

    49 

    50 all_feature_names = [

    51     "nested_scopes",

    52     "generators",

    53     "division",

    54     "absolute_import",

    55     "with_statement",

    56     "print_function",

    57     "unicode_literals",

    58 ]

    59 

    60 __all__ = ["all_feature_names"] + all_feature_names

    61 

    62 # The CO_xxx symbols are defined here under the same names used by

    63 # compile.h, so that an editor search will find them here.  However,

    64 # they're not exported in __all__, because they don't really belong to

    65 # this module.

    66 CO_NESTED            = 0x0010   # nested_scopes

    67 CO_GENERATOR_ALLOWED = 0        # generators (obsolete, was 0x1000)

    68 CO_FUTURE_DIVISION   = 0x2000   # division

    69 CO_FUTURE_ABSOLUTE_IMPORT = 0x4000 # perform absolute imports by default

    70 CO_FUTURE_WITH_STATEMENT  = 0x8000   # with statement

    71 CO_FUTURE_PRINT_FUNCTION  = 0x10000   # print function

    72 CO_FUTURE_UNICODE_LITERALS = 0x20000 # unicode string literals

    73 

    74 class _Feature:

    75     def __init__(self, optionalRelease, mandatoryRelease, compiler_flag):

    76         self.optional = optionalRelease

    77         self.mandatory = mandatoryRelease

    78         self.compiler_flag = compiler_flag

    79 

    80     def getOptionalRelease(self):

    81         """Return first release in which this feature was recognized.

    82 

    83         This is a 5-tuple, of the same form as sys.version_info.

    84         """

    85 

    86         return self.optional

    87 

    88     def getMandatoryRelease(self):

    89         """Return release in which this feature will become mandatory.

    90 

    91         This is a 5-tuple, of the same form as sys.version_info, or, if

    92         the feature was dropped, is None.

    93         """

    94 

    95         return self.mandatory

    96 

    97     def __repr__(self):

    98         return "_Feature" + repr((self.optional,

    99                                   self.mandatory,

   100                                   self.compiler_flag))

   101 

   102 nested_scopes = _Feature((2, 1, 0, "beta",  1),

   103                          (2, 2, 0, "alpha", 0),

   104                          CO_NESTED)

   105 

   106 generators = _Feature((2, 2, 0, "alpha", 1),

   107                       (2, 3, 0, "final", 0),

   108                       CO_GENERATOR_ALLOWED)

   109 

   110 division = _Feature((2, 2, 0, "alpha", 2),

   111                     (3, 0, 0, "alpha", 0),

   112                     CO_FUTURE_DIVISION)

   113 

   114 absolute_import = _Feature((2, 5, 0, "alpha", 1),

   115                            (2, 7, 0, "alpha", 0),

   116                            CO_FUTURE_ABSOLUTE_IMPORT)

   117 

   118 with_statement = _Feature((2, 5, 0, "alpha", 1),

   119                           (2, 6, 0, "alpha", 0),

   120                           CO_FUTURE_WITH_STATEMENT)

   121 

   122 print_function = _Feature((2, 6, 0, "alpha", 2),

   123                           (3, 0, 0, "alpha", 0),

   124                           CO_FUTURE_PRINT_FUNCTION)

   125 

   126 unicode_literals = _Feature((2, 6, 0, "alpha", 2),

   127                             (3, 0, 0, "alpha", 0),

   128                             CO_FUTURE_UNICODE_LITERALS)