From 713a8e015e3e3f7dfa8eb83354ae43d4be4c93fa Mon Sep 17 00:00:00 2001
From: Cagtay Fabry <43667554+CagtayFabry@users.noreply.github.com>
Date: Tue, 22 Jun 2021 10:00:00 +0200
Subject: [PATCH] add dataclass_nested_eq decorator (#378)

* add `dataclass_nested_eq` decorator

* decorate SpatialData with `dataclass_nested_eq`

* update CHANGELOG.md

* docstring

* formatting
---
 CHANGELOG.md      |  2 ++
 weldx/geometry.py |  1 +
 weldx/util.py     | 42 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 45 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 016019273..b143ff898 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,8 @@
 - added `WeldxFile` wrapper to handle asdf files with history and schemas more
   easily. [[#341]](https://github.com/BAMWelDX/weldx/pull/341).
 - add `"step"` as additional method to `util.xr_interp_like` [[#363]](https://github.com/BAMWelDX/weldx/pull/363)
+- add `util.compare_nested_eq` decorator for dataclasses with array-like
+  fields [[#378]](https://github.com/BAMWelDX/weldx/pull/378)
 
 ### changes
 
diff --git a/weldx/geometry.py b/weldx/geometry.py
index 7006449a0..275e86bd8 100644
--- a/weldx/geometry.py
+++ b/weldx/geometry.py
@@ -2294,6 +2294,7 @@ def spatial_data(
 # SpatialData --------------------------------------------------------------------------
 
 
+@ut.dataclass_nested_eq
 @dataclass
 class SpatialData:
     """Represent 3D point cloud data with optional triangulation.
diff --git a/weldx/util.py b/weldx/util.py
index d303ab3ef..31aa079b7 100644
--- a/weldx/util.py
+++ b/weldx/util.py
@@ -128,6 +128,48 @@ def inner_decorator(
     return inner_decorator
 
 
+def dataclass_nested_eq(original_class):
+    """Set class :code:`__eq__` using :code:`util.compare_nested` on :code:`__dict__`.
+
+    Useful for implementing :code:`__eq__` on classes
+    created with :code:`@dataclass` decorator.
+
+    Parameters
+    ----------
+    original_class:
+        original class to decorate
+
+    Returns
+    -------
+    type
+        The class with overridden :code:`__eq__` function.
+
+    Examples
+    --------
+    A simple dataclass could look like this::
+
+        @dataclass_nested_eq
+        @dataclass
+        class A:
+            a: np.ndarray
+
+        a = A(np.arange(3))
+        b = A(np.arange(3))
+        assert a==b
+
+    """
+
+    def new_eq(self, other):
+        if not isinstance(other, type(self)):
+            return False
+
+        return compare_nested(self.__dict__, other.__dict__)
+
+    # set new eq function
+    original_class.__eq__ = new_eq  # Set the class' __eq__ to the new one
+    return original_class
+
+
 def _clean_notebook(file: Union[str, Path]):  # pragma: no cover
     """Clean ID metadata, output and execution count from jupyter notebook cells.