1 # module which helps with porting to Python 3
3 # Copyright (C) Lumir Balhar <lbalhar@redhat.com> 2017
5 # This program is free software; you can redistribute it and/or modify
6 # it under the terms of the GNU General Public License as published by
7 # the Free Software Foundation; either version 3 of the License, or
8 # (at your option) any later version.
10 # This program is distributed in the hope that it will be useful,
11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 # GNU General Public License for more details.
15 # You should have received a copy of the GNU General Public License
16 # along with this program. If not, see <http://www.gnu.org/licenses/>.
18 """module which helps with porting to Python 3"""
22 PY3 = sys.version_info[0] == 3
25 # Sometimes in PY3 we have variables whose content can be 'bytes' or
26 # 'str' and we can't be sure which. Generally this is because the
27 # code variable can be initialised (or reassigned) a value from different
28 # api(s) or functions depending on complex conditions or logic. Or another
29 # common case is in PY2 the variable is 'type <str>' and in PY3 it is
30 # 'class <str>' and the function to use e.g. b64encode requires 'bytes'
31 # in PY3. In such cases it would be nice to avoid excessive testing in
32 # the client code. Calling such a helper function should be avoided
33 # if possible but sometimes this just isn't possible.
34 # If a 'str' object is passed in it is encoded using 'utf8' or if 'bytes'
35 # is passed in it is returned unchanged.
36 # Using this function is PY2/PY3 code should ensure in most cases
37 # the PY2 code runs unchanged in PY2 whereas the code in PY3 possibly
38 # encodes the variable (see PY2 implementation of this function below)
39 def get_bytes(bytesorstring):
41 if isinstance(bytesorstring, str):
42 tmp = bytesorstring.encode('utf8')
43 elif not isinstance(bytesorstring, bytes):
44 raise ValueError('Expected byte or string for %s:%s' % (type(bytesorstring), bytesorstring))
47 # helper function to get a string from a variable that maybe 'str' or
48 # 'bytes' if 'bytes' then it is decoded using 'utf8'. If 'str' is passed
49 # it is returned unchanged
50 # Using this function is PY2/PY3 code should ensure in most cases
51 # the PY2 code runs unchanged in PY2 whereas the code in PY3 possibly
52 # decodes the variable (see PY2 implementation of this function below)
53 def get_string(bytesorstring):
55 if isinstance(bytesorstring, bytes):
56 tmp = bytesorstring.decode('utf8')
57 elif not isinstance(bytesorstring, str):
58 raise ValueError('Expected byte of string for %s:%s' % (type(bytesorstring), bytesorstring))
63 Replacement for built-in function cmp that was removed in Python 3
65 Compare the two objects x and y and return an integer according to
66 the outcome. The return value is negative if x < y, zero if x == y
67 and strictly positive if x > y.
70 return (x > y) - (x < y)
72 from urllib.parse import quote as urllib_quote
73 from urllib.parse import urljoin as urllib_join
74 from urllib.request import urlopen as urllib_urlopen
75 from functools import cmp_to_key as cmp_to_key_fn
85 StringIO = io.StringIO
86 def ConfigParser(defaults=None, dict_type=None, allow_no_value=None):
87 from configparser import ConfigParser
88 return ConfigParser(defaults, dict_type, allow_no_value, interpolation=None)
90 # Helper function to return bytes.
91 # if 'unicode' is passed in then it is decoded using 'utf8' and
92 # the result returned. If 'str' is passed then it is returned unchanged.
93 # Using this function is PY2/PY3 code should ensure in most cases
94 # the PY2 code runs unchanged in PY2 whereas the code in PY3 possibly
95 # encodes the variable (see PY3 implementation of this function above)
96 def get_bytes(bytesorstring):
98 if isinstance(bytesorstring, unicode):
99 tmp = bytesorstring.encode('utf8')
100 elif not isinstance(bytesorstring, str):
101 raise ValueError('Expected string for %s:%s' % (type(bytesorstring), bytesorstring))
104 # Helper function to return string.
105 # if 'str' or 'unicode' passed in they are returned unchanged
106 # otherwise an exception is generated
107 # Using this function is PY2/PY3 code should ensure in most cases
108 # the PY2 code runs unchanged in PY2 whereas the code in PY3 possibly
109 # decodes the variable (see PY3 implementation of this function above)
110 def get_string(bytesorstring):
112 if not(isinstance(bytesorstring, str) or isinstance(bytesorstring, unicode)):
113 raise ValueError('Expected str or unicode for %s:%s' % (type(bytesorstring), bytesorstring))
117 if sys.version_info < (2, 7):
118 def cmp_to_key_fn(mycmp):
120 """Convert a cmp= function into a key= function"""
124 def __init__(self, obj, *args):
127 def __lt__(self, other):
128 return mycmp(self.obj, other.obj) < 0
130 def __gt__(self, other):
131 return mycmp(self.obj, other.obj) > 0
133 def __eq__(self, other):
134 return mycmp(self.obj, other.obj) == 0
136 def __le__(self, other):
137 return mycmp(self.obj, other.obj) <= 0
139 def __ge__(self, other):
140 return mycmp(self.obj, other.obj) >= 0
142 def __ne__(self, other):
143 return mycmp(self.obj, other.obj) != 0
146 raise TypeError('hash not implemented')
149 from functools import cmp_to_key as cmp_to_key_fn
151 from urllib import quote as urllib_quote
152 from urllib import urlopen as urllib_urlopen
153 from urlparse import urljoin as urllib_join
156 integer_types = (int, long)
157 string_types = basestring
163 StringIO = cStringIO.StringIO
164 from ConfigParser import ConfigParser