Added the mistake_enum.py (Enum for the type of mistakes, to mark words with)...

Added the mistake_enum.py (Enum for the type of mistakes, to mark words with) and added mistake properties/getters/setters in words.py.

umbra/mistake_enum.py

+from enum import Enum
+
+
+class NoValue(Enum):
+    """Enum class for which the value is not important. The __repr__ hides
+    the unimportant value, when a NoValue Enum is printed.
+    """
+    def __repr__(self):
+        return '<%s.%s>' % (self.__class__.__name__, self.name)
+
+
+class Mistake(Enum):
+    """Enum for all types of mistakes that can be made in the shadow task."""
+    PHONETIC = "phonetic"
+    REPETITION = "repetition"
+    SEMANTIC = "semantic"
+    SKIPPED = "skipped"  # For source words that are not shadowed
+    RANDOM = "random"  # For shadow words that do not reflect a source word

umbra/words.py

+from mistake_enum import Mistake
+
+
 class Word:
     def __init__(self, word, onset, offset):
         self._word = word
         self._onset = onset
         self._offset = offset
         self._anchor = None
+        self._mistake = None
 
     def __str__(self):
         return "%s | %f | %f" % (self._word, self._onset, self._offset)
@@ -14,7 +18,6 @@ class Word:
     def __eq__(self, word):
         return self._word == word.word
 
-
     @property
     def word(self):
         """Getter for the word.
@@ -51,6 +54,29 @@ class Word:
         """
         return self._anchor
 
+    @property
+    def mistake(self):
+        """Getter for the mistake.
+
+        Return:
+            mistake: Enum of the type of mistake that this word is. None if
+            not marked as a mistake.
+        """
+        return self._mistake
+
+    @mistake.setter
+    def mistake(self, mistake):
+        """Setter for the type of mistake.
+
+        Args:
+            mistake: Mistake Enum
+        """
+        self._set_mistake(mistake)
+
+    def _set_mistake(self, mistake):
+        """Mistake setter. Has to be overridden in the subclass."""
+        raise NotImplementedError
+
     def is_anchor(self):
         """Whether this word is a anchor or not.
 
@@ -61,7 +87,7 @@ class Word:
 
     @anchor.setter
     def anchor(self, anchor):
-        """ Anchor this Word object to another Word object.
+        """Anchor this Word object to another Word object.
 
         Args:
              anchor: Word instance to anchor to
@@ -127,6 +153,18 @@ class ShadowWord(Word):
         """
         return self._source is not None
 
+    def _set_mistake(self, mistake):
+        """Setter for the type of mistake. Only works if the word is not marked
+        as correct yet and if mistake is not SKIPPED.
+
+        Args:
+            mistake: Mistake Enum
+        """
+        assert self._correct is False
+        assert mistake != Mistake.SKIPPED
+        self._mistake(mistake)
+
+
 class SourceWord(Word):
     def __init__(self, word, onset, offset):
         super().__init__(word, onset, offset)
@@ -150,6 +188,15 @@ class SourceWord(Word):
         """
         self._shadowed = value
 
+    def _set_mistake(self, mistake):
+        """Setter for the type of mistake. Only works if mistake is not RANDOM.
+
+        Args:
+            mistake: Mistake Enum
+        """
+        assert mistake != Mistake.RANDOM
+        self._mistake(mistake)
+
 
 class Sentence(list):
     def __init__(self, words):