-# Copyright (c) 2010-2011 testtools developers. See LICENSE for details.
+# Copyright (c) 2010-2012 testtools developers. See LICENSE for details.
__all__ = [
'safe_hasattr',
properties.
"""
return getattr(obj, attr, _marker) is not _marker
+
+
+def map_values(function, dictionary):
+ """Map ``function`` across the values of ``dictionary``.
+
+ :return: A dict with the same keys as ``dictionary``, where the value
+ of each key ``k`` is ``function(dictionary[k])``.
+ """
+ return dict((k, function(dictionary[k])) for k in dictionary)
+
+
+def filter_values(function, dictionary):
+ """Filter ``dictionary`` by its values using ``function``."""
+ return dict((k, v) for k, v in dictionary.items() if function(v))
+
+
+def dict_subtract(a, b):
+ """Return the part of ``a`` that's not in ``b``."""
+ return dict((k, a[k]) for k in set(a) - set(b))
+
+
+def list_subtract(a, b):
+ """Return a list ``a`` without the elements of ``b``.
+
+ If a particular value is in ``a`` twice and ``b`` once then the returned
+ list then that value will appear once in the returned list.
+ """
+ a_only = list(a)
+ for x in b:
+ if x in a_only:
+ a_only.remove(x)
+ return a_only