Implemented explicit slots on all selection classes.

This helps satisfy GitHub #403.

abjad/tools/selectiontools/ContiguousSelection.py

@@ -13,6 +13,11 @@ class ContiguousSelection(Selection):
     r'''A time-contiguous selection of components.
     '''
 
+    ### CLASS VARIABLES ###
+
+    __slots__ = (
+        )
+
     ### INITIALIZER ###
 
     def __init__(self, music=None):
@@ -721,4 +726,4 @@ def partition_by_durations_not_less_than(
             fill='greater',
             in_seconds=in_seconds,
             overhang=overhang,
-            )
+            )

abjad/tools/selectiontools/LogicalTie.py

@@ -5,8 +5,7 @@
 from abjad.tools.topleveltools import attach
 from abjad.tools.topleveltools import detach
 from abjad.tools.topleveltools import mutate
-from abjad.tools.selectiontools.ContiguousSelection \
-    import ContiguousSelection
+from abjad.tools.selectiontools.ContiguousSelection import ContiguousSelection
 
 
 class LogicalTie(ContiguousSelection):
@@ -26,6 +25,11 @@ class LogicalTie(ContiguousSelection):
 
     '''
 
+    ### CLASS VARIABLES ###
+
+    __slots__ = (
+        ) 
+
     ### PRIVATE METHODS ###
 
     def _add_or_remove_notes_to_achieve_written_duration(
@@ -381,4 +385,4 @@ def to_tuplet(
         #detach(spannertools.Tie, tuplet)
 
         # return tuplet
-        return tuplet
+        return tuplet

abjad/tools/selectiontools/Selection.py

@@ -79,6 +79,19 @@ def __getitem__(self, expr):
             result = selection
         return result
 
+    def __getstate__(self):
+        r'''Gets state of selection.
+
+        Returns dictionary.
+        '''
+        if hasattr(self, '__dict__'):
+            return vars(self)
+        state = {}
+        for class_ in type(self).__mro__:
+            for slot in getattr(class_, '__slots__', ()):
+                state[slot] = getattr(self, slot, None)
+        return state
+
     def __hash__(self):
         r'''Hashes selection.
 
@@ -160,6 +173,14 @@ def __repr__(self):
         '''
         return '{}{!r}'.format(type(self).__name__, self._music)
 
+    def __setstate__(self, state):
+        r'''Sets state of selection.
+
+        Returns none.
+        '''
+        for key, value in state.items():
+            setattr(self, key, value)
+
     ### PRIVATE PROPERTIES ###
 
     @property

abjad/tools/selectiontools/SliceSelection.py

@@ -31,6 +31,11 @@ class SliceSelection(ContiguousSelection):
 
     '''
 
+    ### CLASS VARIABLES ###
+
+    __slots__ = (
+        )
+
     ### INITIALIZER ###
 
     # TODO: assert all are contiguous components in same parent
@@ -74,4 +79,4 @@ def _give_position_in_parent_to_container(self, container):
         if parent is not None:
             parent._music.__setitem__(slice(start, start), [container])
             container._set_parent(parent)
-            self._set_parents(None)
+            self._set_parents(None)