added auto_sync feature

tests/test_variableparameters.py

@@ -342,3 +342,39 @@ def test_filter():
 
     mat = np.random.rand(70, 12, 11)
     assert f(mat.reshape(len(conf), 11), squeeze=False).shape == (12, 1, 1, 3, 11)
+
+
+def test_auto_sync():
+    @vdataclass
+    class Conf:
+        x: Variable = vfield()
+        y: Variable = vfield(default=[7, 8, 9])
+        z: Variable = vfield(default=7.5e-9, auto_sync=True)
+        w: Variable = vfield(default=7568.4e6, auto_sync=True)
+
+    conf = Conf([1, 2, 3])
+    assert len(conf) == 9
+
+    @vdataclass
+    class Conf:
+        x: Variable = vfield()
+        y: Variable = vfield(default=[7, 8, 9])
+        z: Variable = vfield(default=7.5e-9, auto_sync=True)
+
+    conf = Conf(1, z=[1, 2, 3])
+    assert len(conf) == 3
+
+    conf.z = [0, 5]
+    assert len(conf) == 6
+    assert conf.y(0) == 7
+    assert conf.y(1) == 7
+    assert conf.y(2) == 8
+    assert conf.y(3) == 8
+    assert conf.y(4) == 9
+    assert conf.y(5) == 9
+    assert conf.z(0) == 0
+    assert conf.z(1) == 5
+    assert conf.z(2) == 0
+    assert conf.z(3) == 5
+    assert conf.z(4) == 0
+    assert conf.z(5) == 5