Add warnings module

pyphi/warnings.py

@@ -0,0 +1,28 @@
+# warnings.py
+
+"""PyPhi warnings."""
+
+import warnings
+
+
+class PyPhiWarning(UserWarning):
+    """Class for PyPhi warnings."""
+
+
+def warn_about_tie_serialization(
+    name, serialize=False, deserialize=False, stacklevel=3
+):
+    # XOR; exactly one of serialize or deserialize must be True
+    if not serialize ^ deserialize:
+        raise ValueError("Exactly one of ``serialize``, ``deserialize`` must be True")
+    if serialize:
+        msg = (
+            "Serializing ties to JSON in {name} is not currently "
+            "supported; tie information will be lost."
+        )
+    if deserialize:
+        msg = (
+            "Deserializing ties in {name} from JSON is not currently "
+            "supported; tie information was lost during serialization."
+        )
+    warnings.warn(msg.format(name=name), UserWarning, stacklevel=stacklevel)