experimental str support in VariableParameter

tests/test_variableparameters.py

@@ -94,6 +94,21 @@ def test_constant_number():
         conf.y(1)
 
 
+def test_non_numbers():
+    @vdataclass
+    class Conf:
+        x: Variable = vfield(default=["Hello", "World"])
+        y: Variable = vfield()
+
+    conf = Conf(y=("a", "b", "c"))
+    assert conf.x(0) == "Hello"
+    assert conf.y(0) == "a"
+    assert conf.y(1) == "b"
+    assert conf.y(2) == "c"
+
+    assert conf.x(3) == "World"
+
+
 def test_constant_list():
     """classes with constant fields don't increase size and always return the constant"""