Check for uniqueness of names in ExpressionState

1 files changed, 10 insertions, 3 deletions

diff --git a/polymatrix/expressionstate/mixins.py b/polymatrix/expressionstate/mixins.py
index 9b4817b..f5a0c25 100644
--- a/polymatrix/expressionstate/mixins.py
+++ b/polymatrix/expressionstate/mixins.py
@@ -39,9 +39,16 @@ class ExpressionStateMixin(
         if not isinstance(var, Variable):
             raise ValueError("State can only index object of type Variable!")
 
-        # Check if already in there
-        if var in self.indices.keys():
-            return self, self.indices[var]
+        for v, irange in self.indices.items():
+            # Check if already in there
+            if v == var:
+                return self, irange
+
+            # Check that there is not another variable with the same name
+            if v.name == var.name:
+                raise ValueError("Variable must have unique names! "
+                                 f"There is already a variable named {var.name} "
+                                 f"with shape {v.shape}")
 
         # If not save new index
         size = prod(var.shape)