Dynamically switch completion style based on result count

- Added max_column_completion_items setting (default 7) to configure the threshold.
- Updated Cmd.complete to switch between CompleteStyle.COLUMN and CompleteStyle.MULTI_COLUMN.
- Added test case to verify the behavior.

Author: tleonhardt

cmd2/cmd2.py

@@ -428,6 +428,10 @@ def _(event: Any) -> None:  # pragma: no cover
         # not include the description value of the CompletionItems.
         self.max_completion_items: int = 50
 
+        # The maximum number of completion results to display in a single column (CompleteStyle.COLUMN).
+        # If the number of results exceeds this, CompleteStyle.MULTI_COLUMN will be used.
+        self.max_column_completion_items: int = 7
+
         # A dictionary mapping settable names to their Settable instance
         self._settables: dict[str, Settable] = {}
         self._always_prefix_settables: bool = False
@@ -1219,6 +1223,11 @@ def allow_style_type(value: str) -> ru.AllowStyle:
         self.add_settable(
             Settable('max_completion_items', int, "Maximum number of CompletionItems to display during tab completion", self)
         )
+        self.add_settable(
+            Settable(
+                'max_column_completion_items', int, "Maximum number of completion results to display in a single column", self
+            )
+        )
         self.add_settable(Settable('quiet', bool, "Don't print nonessential feedback", self))
         self.add_settable(Settable('scripts_add_to_history', bool, 'Scripts and pyscripts add commands to history', self))
         self.add_settable(Settable('timing', bool, "Report execution times", self))
@@ -2500,6 +2509,12 @@ def complete(
                     self.display_matches.sort(key=self.default_sort_key)
                     self.matches_sorted = True
 
+                # Swap between COLUMN and MULTI_COLUMN style based on the number of matches
+                if len(self.completion_matches) > self.max_column_completion_items:
+                    self.session.complete_style = CompleteStyle.MULTI_COLUMN
+                else:
+                    self.session.complete_style = CompleteStyle.COLUMN
+
             try:
                 return self.completion_matches[state]
             except IndexError:

tests/test_dynamic_complete_style.py

@@ -0,0 +1,58 @@
+import pytest
+from prompt_toolkit.shortcuts import CompleteStyle
+
+import cmd2
+
+
+class AutoStyleApp(cmd2.Cmd):
+    def __init__(self):
+        super().__init__()
+
+    def do_foo(self, args):
+        pass
+
+    def complete_foo(self, text, line, begidx, endidx):
+        # Return 10 items
+        return [f'item{i}' for i in range(10) if f'item{i}'.startswith(text)]
+
+    def do_bar(self, args):
+        pass
+
+    def complete_bar(self, text, line, begidx, endidx):
+        # Return 5 items
+        return [f'item{i}' for i in range(5) if f'item{i}'.startswith(text)]
+
+
+@pytest.fixture
+def app():
+    return AutoStyleApp()
+
+
+def test_dynamic_complete_style(app):
+    # Default max_column_completion_items is 7
+    assert app.max_column_completion_items == 7
+
+    # Complete 'foo' which has 10 items (> 7)
+    # text='item', state=0, line='foo item', begidx=4, endidx=8
+    app.complete('item', 0, 'foo item', 4, 8)
+    assert app.session.complete_style == CompleteStyle.MULTI_COLUMN
+
+    # Complete 'bar' which has 5 items (<= 7)
+    app.complete('item', 0, 'bar item', 4, 8)
+    assert app.session.complete_style == CompleteStyle.COLUMN
+
+
+def test_dynamic_complete_style_custom_limit(app):
+    # Change limit to 3
+    app.max_column_completion_items = 3
+
+    # Complete 'bar' which has 5 items (> 3)
+    app.complete('item', 0, 'bar item', 4, 8)
+    assert app.session.complete_style == CompleteStyle.MULTI_COLUMN
+
+    # Change limit to 15
+    app.max_column_completion_items = 15
+
+    # Complete 'foo' which has 10 items (<= 15)
+    app.complete('item', 0, 'foo item', 4, 8)
+    assert app.session.complete_style == CompleteStyle.COLUMN