feat(MLRsearch): MLRsearch v7

[csit.git] / resources / libraries / python / MLRsearch / dataclass / field.py

diff --git a/resources/libraries/python/MLRsearch/dataclass/field.py b/resources/libraries/python/MLRsearch/dataclass/field.py
new file mode 100644 (file)
index 0000000..55d9d08
--- /dev/null
+++ b/resources/libraries/python/MLRsearch/dataclass/field.py
@@ -0,0 +1,44 @@
+# Copyright (c) 2023 Cisco and/or its affiliates.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Module defining secondary_field function.
+
+Just a shrothand for frequently repeated expression.
+
+The main point is that this dataclass field is not used in init.
+Maybe it is a derived value of a frozen dataclass.
+Maybe it is a cache to help avoiding repeated computation.
+Maybe it is a temporary value stored in one method and read in another method.
+In any case, the caller does not need to know it is here,
+so it is excluded from repr, hashing, ordering and similar.
+"""
+
+from dataclasses import Field, field
+
+
+def secondary_field() -> Field:
+    """Return newly created Field with non-default arguments
+
+    In practice, it seems to be fine to reuse the resulting Field instance
+    when defining multiple dataclass fields,
+    but we keep this as a function to improve readability.
+
+    :returns: A new Field instance useful for secondary fields.
+    :rtype: Field
+    """
+    return field(
+        default=None,
+        init=False,
+        repr=False,
+        compare=False,
+    )