From 19ebccc448ed7fd6fd903827c62d6620388f9692 Mon Sep 17 00:00:00 2001
From: tylerflex <tyler@flexcompute.com>
Date: Thu, 28 Apr 2022 13:50:47 -0700
Subject: [PATCH 1/2] copy is deep by default

---
 tests/test_components.py  | 33 +++++++++++++++++++++++++++++++++
 tidy3d/components/base.py |  4 ++++
 2 files changed, 37 insertions(+)

diff --git a/tests/test_components.py b/tests/test_components.py
index 87bce592d6..dce4e8a7cb 100644
--- a/tests/test_components.py
+++ b/tests/test_components.py
@@ -836,3 +836,36 @@ def test_mode_object_syms():
             )
         ],
     )
+
+
+def test_deep_copy():
+    """Make sure deep copying works as expceted with defaults."""
+    b = Box(size=(1, 1, 1))
+    m = Medium(permittivity=1)
+
+    s = Structure(
+        geometry=b,
+        medium=m,
+    )
+
+    s_shallow = s.copy(deep=False)
+
+    # with shallow copy, these should be the same objects
+    assert id(s.geometry) == id(s_shallow.geometry)
+    assert id(s.medium) == id(s_shallow.medium)
+
+    s_deep = s.copy(deep=True)
+
+    # with deep copy, these should be different objects
+    assert id(s.geometry) != id(s_deep.geometry)
+    assert id(s.medium) != id(s_deep.medium)
+
+    # default should be deep
+    s_default = s.copy()
+    assert id(s.geometry) != id(s_default.geometry)
+    assert id(s.medium) != id(s_default.medium)
+
+    # make sure other kwargs work, here we update the geometry to a sphere and shallow copy medium
+    s_kwargs = s.copy(deep=False, update={"geometry": Sphere(radius=1.0)})
+    assert id(s.medium) == id(s_kwargs.medium)
+    assert id(s.geometry) != id(s_kwargs.geometry)
diff --git a/tidy3d/components/base.py b/tidy3d/components/base.py
index 8b4a03f4f0..12eec55071 100644
--- a/tidy3d/components/base.py
+++ b/tidy3d/components/base.py
@@ -61,6 +61,10 @@ class Config:  # pylint: disable=too-few-public-methods
             complex: lambda x: ComplexNumber(real=x.real, imag=x.imag),
         }
 
+    def copy(self, deep: bool = True, **kwargs) -> "Self":
+        """Copy a Tidy3dBaseModel.  With ``deep=True`` as default."""
+        return super().copy(deep=deep, **kwargs)
+
     def help(self, methods: bool = False) -> None:
         """Prints message describing the fields and methods of a :class:`Tidy3dBaseModel`.
 

From d0a2ebcd12d23c35d0704fe41bf866c903f82421 Mon Sep 17 00:00:00 2001
From: tylerflex <tyler@flexcompute.com>
Date: Thu, 28 Apr 2022 15:40:26 -0700
Subject: [PATCH 2/2] added some extra tests

---
 tests/test_components.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/tests/test_components.py b/tests/test_components.py
index dce4e8a7cb..745abe049f 100644
--- a/tests/test_components.py
+++ b/tests/test_components.py
@@ -869,3 +869,21 @@ def test_deep_copy():
     s_kwargs = s.copy(deep=False, update={"geometry": Sphere(radius=1.0)})
     assert id(s.medium) == id(s_kwargs.medium)
     assert id(s.geometry) != id(s_kwargs.geometry)
+
+    # behavior of modifying attributes
+    s_default = s.copy()
+    s_default.geometry = Sphere(radius=1.0)
+    assert id(s.geometry) != id(s_default.geometry)
+
+    s_shallow = s.copy(deep=False)
+    s_shallow.geometry = Sphere(radius=1.0)
+    assert id(s.geometry) != id(s_shallow.geometry)
+
+    # behavior of modifying attributes of attributes
+    s_default = s.copy()
+    s_default.geometry.size = (2, 2, 2)
+    assert id(s.geometry) != id(s_default.geometry)
+
+    s_shallow = s.copy(deep=False)
+    s_shallow.geometry.size = (2, 2, 2)
+    assert id(s.geometry) == id(s_shallow.geometry)