Merge pull request #17 from ihmpdcc/pr-16

Pull request from @schwager-hsph merged along with another commit.

Author: victor73

CHANGES

@@ -1,3 +1,10 @@
+cutlass 0.6
+
+ * Added convenience methods to make objects hashable, equal-able.
+   Contributed by schwager-hsph@github.com.
+
+ - Victor <victor73@github.com>  Thu, l9 Nov 2015 12:00:00 -0400
+
 cutlass 0.5
 
  * Fixed requirement for both 'part_of' and 'subset_of' linkages

cutlass/Base.py

@@ -271,3 +271,31 @@ def delete(self):
                               "Reason: %s" % visit_node_id, e.strerror)
 
         return success
+
+
+    def __str__(self):
+        _id = "no ID" if not self._id else self._id[-8:]
+        name = None
+        for attr in ("_name", "_rand_subject_id", "_date", "_local_file"):
+            if hasattr(self, attr):
+                name = getattr(self, attr)
+                break
+        if name:
+            return "<{} `{}' ({})>".format(self.__class__.__name__, name, _id)
+        else:
+            return "<{} ({})>".format(self.__class__.__name__, _id)
+
+
+    __repr__ = __str__
+
+
+    def __hash__(self):
+        if not self._id:
+            raise TypeError("unhashable; must have ID: '{}')".format(str(self)))
+        return hash(self._id)
+
+
+    def __eq__(self, other):
+        if self._id and other._id:
+            return self._id == other._id
+        return False