Make Lib/crypt.py meet PEP 8 standards. This also led to a tweak in the new API

by making methods() into a module attribute as it is statically calculated.

Lib/crypt.py

@@ -1,61 +1,57 @@
-'''Wrapper to the POSIX crypt library call and associated functionality.
-'''
+"""Wrapper to the POSIX crypt library call and associated functionality."""
 
 import _crypt
-
-saltchars = 'abcdefghijklmnopqrstuvwxyz'
-saltchars += saltchars.upper()
-saltchars += '0123456789./'
+import string
+from random import choice
+from collections import namedtuple
 
 
-class _MethodClass:
-    '''Class representing a salt method per the Modular Crypt Format or the
-    legacy 2-character crypt method.'''
-    def __init__(self, name, ident, salt_chars, total_size):
-        self.name = name
-        self.ident = ident
-        self.salt_chars = salt_chars
-        self.total_size = total_size
+_saltchars = string.ascii_letters + string.digits + './'
+
+
+class _Method(namedtuple('_Method', 'name ident salt_chars total_size')):
+
+    """Class representing a salt method per the Modular Crypt Format or the
+    legacy 2-character crypt method."""
 
     def __repr__(self):
-        return '<crypt.METHOD_%s>' % self.name
+        return '<crypt.METHOD_{}>'.format(self.name)
+
+
+
+def mksalt(method=None):
+    """Generate a salt for the specified method.
+
+    If not specified, the strongest available method will be used.
+
+    """
+    if method is None:
+        method = methods[0]
+    s = '${}$'.format(method.ident) if method.ident else ''
+    s += ''.join(choice(_saltchars) for _ in range(method.salt_chars))
+    return s
+
+
+def crypt(word, salt=None):
+    """Return a string representing the one-way hash of a password, with a salt
+    prepended.
+
+    If ``salt`` is not specified or is ``None``, the strongest
+    available method will be selected and a salt generated.  Otherwise,
+    ``salt`` may be one of the ``crypt.METHOD_*`` values, or a string as
+    returned by ``crypt.mksalt()``.
+
+    """
+    if salt is None or isinstance(salt, _Method):
+        salt = mksalt(salt)
+    return _crypt.crypt(word, salt)
 
 
 #  available salting/crypto methods
-METHOD_CRYPT = _MethodClass('CRYPT', None, 2, 13)
-METHOD_MD5 = _MethodClass('MD5', '1', 8, 34)
-METHOD_SHA256 = _MethodClass('SHA256', '5', 16, 63)
-METHOD_SHA512 = _MethodClass('SHA512', '6', 16, 106)
+METHOD_CRYPT = _Method('CRYPT', None, 2, 13)
+METHOD_MD5 = _Method('MD5', '1', 8, 34)
+METHOD_SHA256 = _Method('SHA256', '5', 16, 63)
+METHOD_SHA512 = _Method('SHA512', '6', 16, 106)
 
-
-def methods():
-    '''Return a list of methods that are available in the platform ``crypt()``
-    library, sorted from strongest to weakest.  This is guaranteed to always
-    return at least ``[METHOD_CRYPT]``'''
-    method_list = [ METHOD_SHA512, METHOD_SHA256, METHOD_MD5 ]
-    ret = [ method for method in method_list
-            if len(crypt('', method)) == method.total_size ]
-    ret.append(METHOD_CRYPT)
-    return ret
-
-
-def mksalt(method = None):
-    '''Generate a salt for the specified method.  If not specified, the
-    strongest available method will be used.'''
-    import random
-
-    if method == None: method = methods()[0]
-    s = '$%s$' % method.ident if method.ident else ''
-    s += ''.join([ random.choice(saltchars) for x in range(method.salt_chars) ])
-    return(s)
-
-
-def crypt(word, salt = None):
-    '''Return a string representing the one-way hash of a password, preturbed
-    by a salt.  If ``salt`` is not specified or is ``None``, the strongest
-    available method will be selected and a salt generated.  Otherwise,
-    ``salt`` may be one of the ``crypt.METHOD_*`` values, or a string as
-    returned by ``crypt.mksalt()``.'''
-    if salt == None: salt = mksalt()
-    elif isinstance(salt, _MethodClass): salt = mksalt(salt)
-    return(_crypt.crypt(word, salt))
+methods = [METHOD_SHA512, METHOD_SHA256, METHOD_MD5, METHOD_CRYPT]
+methods[:-1] = [m for m in methods[:-1] if len(crypt('', m)) == m.total_size]