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 ]

    57 

    58 __all__ = ["all_feature_names"] + all_feature_names

    59 

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

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

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

    63 # this module.

    64 CO_NESTED            = 0x0010   # nested_scopes

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

    66 CO_FUTURE_DIVISION   = 0x2000   # division

    67 CO_FUTURE_ABSOLUTE_IMPORT = 0x4000 # perform absolute imports by default

    68 CO_FUTURE_WITH_STATEMENT  = 0x8000   # with statement

    69 

    70 class _Feature:

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

    72         self.optional = optionalRelease

    73         self.mandatory = mandatoryRelease

    74         self.compiler_flag = compiler_flag

    75 

    76     def getOptionalRelease(self):

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

    78 

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

    80         """

    81 

    82         return self.optional

    83 

    84     def getMandatoryRelease(self):

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

    86 

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

    88         the feature was dropped, is None.

    89         """

    90 

    91         return self.mandatory

    92 

    93     def __repr__(self):

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

    95                                   self.mandatory,

    96                                   self.compiler_flag))

    97 

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

    99                          (2, 2, 0, "alpha", 0),

   100                          CO_NESTED)

   101 

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

   103                       (2, 3, 0, "final", 0),

   104                       CO_GENERATOR_ALLOWED)

   105 

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

   107                     (3, 0, 0, "alpha", 0),

   108                     CO_FUTURE_DIVISION)

   109 

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

   111                            (2, 7, 0, "alpha", 0),

   112                            CO_FUTURE_ABSOLUTE_IMPORT)

   113 

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

   115                           (2, 6, 0, "alpha", 0),

   116                           CO_FUTURE_WITH_STATEMENT)