Made CompletionItem deepcopy-safe. (#1642)

Author: kmvanbrunt

cmd2/completion.py

@@ -1,5 +1,6 @@
 """Provides classes and functions related to command-line completion."""
 
+import copy
 import re
 import sys
 from collections.abc import (
@@ -124,6 +125,19 @@ def __post_init__(self) -> None:
             ru.prepare_objects_for_rendering(*renderable_data),
         )
 
+    def __deepcopy__(self, memo: dict[int, Any]) -> "CompletionItem":
+        """Return a shallow copy of this CompletionItem during a deepcopy operation.
+
+        This is necessary because cmd2 deepcopies argument parsers to keep them unique
+        across command instances. This override prevents the deepcopying of
+        CompletionItems stored within a parser's 'choices' list.
+
+        Since the 'value' and 'table_data' fields may contain complex objects which
+        should not be deep copied, a shallow copy ensures the original object
+        references are preserved.
+        """
+        return copy.copy(self)
+
     def __str__(self) -> str:
         """Return the completion text."""
         return self.text

tests/test_completion.py

@@ -5,6 +5,7 @@
 """
 
 import argparse
+import copy
 import dataclasses
 import enum
 import os
@@ -919,6 +920,36 @@ def test_remove_duplicates() -> None:
     assert new_meta in completions
 
 
+def test_completion_item_deepcopy() -> None:
+    """Test that deepcopy of a CompletionItem preserves identity of its members."""
+
+    class ComplexValue:
+        pass
+
+    value = ComplexValue()
+    table_data = (ComplexValue(),)
+    orig_item = CompletionItem(
+        value=value,
+        text="my_text",
+        display="my_display",
+        display_meta="my_meta",
+        table_data=table_data,
+    )
+
+    # Perform deepcopy
+    copied_item = copy.deepcopy(orig_item)
+
+    # We should have a new object
+    assert copied_item is not orig_item
+
+    # But its member should be the same objects
+    assert copied_item.value is orig_item.value
+    assert copied_item.text is orig_item.text
+    assert copied_item.display is orig_item.display
+    assert copied_item.display_meta is orig_item.display_meta
+    assert copied_item.table_data is orig_item.table_data
+
+
 def test_plain_fields() -> None:
     """Test the plain text fields in CompletionItem."""
     display = "\x1b[31mApple\x1b[0m"