Add support for the matmul (@) operator.

CHANGES.rst

@@ -7,6 +7,8 @@ Changes
 - Allow to use the package with Python 3.13 -- Caution: No security
   audit has been done so far.
 
+- Add support for the matmul (``@``) operator.
+
 
 7.0 (2023-11-17)
 ----------------

src/RestrictedPython/transformer.py

@@ -768,8 +768,8 @@ def visit_BitAnd(self, node):
         return self.node_contents_visit(node)
 
     def visit_MatMult(self, node):
-        """Matrix multiplication (`@`) is currently not allowed."""
-        self.not_allowed(node)
+        """Allow multiplication (`@`)."""
+        return self.node_contents_visit(node)
 
     def visit_BoolOp(self, node):
         """Allow bool operator without restrictions."""

tests/transformer/operators/test_arithmetic_operators.py

@@ -1,4 +1,3 @@
-from RestrictedPython import compile_restricted_eval
 from tests.helper import restricted_eval
 
 
@@ -33,8 +32,12 @@ def test_FloorDiv():
 
 
 def test_MatMult():
-    result = compile_restricted_eval('(8, 3, 5) @ (2, 7, 1)')
-    assert result.errors == (
-        'Line None: MatMult statements are not allowed.',
-    )
-    assert result.code is None
+    class Vector:
+        def __init__(self, values):
+            self.values = values
+
+        def __matmul__(self, other):
+            return sum(x * y for x, y in zip(self.values, other.values))
+
+    assert restricted_eval(
+        'Vector((8, 3, 5)) @ Vector((2, 7, 1))', {'Vector': Vector}) == 42