gh-44968: Add "Reload from Disk" feature to IDLE

Lib/idlelib/idle_test/test_iomenu.py

@@ -2,6 +2,7 @@
 
 from idlelib import iomenu
 import unittest
+import builtins
 from test.support import requires
 from tkinter import Tk
 from idlelib.editor import EditorWindow
@@ -57,6 +58,130 @@ def test_fixnewlines_end(self):
         eq(text.get('1.0', 'end-1c'), 'a\n')
         eq(fix(), 'a'+io.eol_convention)
 
+    def test_reload_no_file(self):
+        # Test reload when no file is associated
+        import tempfile
+        import os
+        from unittest.mock import Mock
+
+        io = self.io
+        # Ensure no filename is set
+        io.filename = None
+
+        # Mock the messagebox.showinfo
+        orig_showinfo = iomenu.messagebox.showinfo
+        showinfo_called = []
+        def mock_showinfo(*args, **kwargs):
+            showinfo_called.append((args, kwargs))
+        iomenu.messagebox.showinfo = mock_showinfo
+
+        try:
+            result = io.reload(None)
+            self.assertEqual(result, "break")
+            self.assertEqual(len(showinfo_called), 1)
+            self.assertIn("No File", showinfo_called[0][0])
+        finally:
+            iomenu.messagebox.showinfo = orig_showinfo
+
+    def test_reload_with_file(self):
+        # Test reload with an actual file
+        import tempfile
+        import os
+
+        io = self.io
+        text = io.editwin.text
+
+        # Create a temporary file
+        with tempfile.NamedTemporaryFile(mode='w', delete=False, suffix='.py') as f:
+            f.write("# Original content\n")
+            temp_filename = f.name
+
+        try:
+            # Load the file
+            io.loadfile(temp_filename)
+            self.assertEqual(text.get('1.0', 'end-1c'), "# Original content\n")
+
+            # Modify the file content externally
+            with builtins.open(temp_filename, 'w') as f:
+                f.write("# Modified content\n")
+
+            # Reload should update the content
+            result = io.reload(None)
+            self.assertEqual(result, "break")
+            self.assertEqual(text.get('1.0', 'end-1c'), "# Modified content\n")
+        finally:
+            os.unlink(temp_filename)
+
+    def test_reload_with_unsaved_changes_cancel(self):
+        # Test reload with unsaved changes and user cancels
+        import tempfile
+        import os
+
+        io = self.io
+        text = io.editwin.text
+
+        # Create a temporary file
+        with tempfile.NamedTemporaryFile(mode='w', delete=False, suffix='.py') as f:
+            f.write("# Original content\n")
+            temp_filename = f.name
+
+        try:
+            # Load the file
+            io.loadfile(temp_filename)
+
+            # Make unsaved changes
+            text.insert('end-1c', "\n# Unsaved change")
+            io.set_saved(False)
+
+            # Mock askokcancel to return False (cancel)
+            orig_askokcancel = iomenu.messagebox.askokcancel
+            iomenu.messagebox.askokcancel = lambda *args, **kwargs: False
+
+            try:
+                result = io.reload(None)
+                self.assertEqual(result, "break")
+                # Content should not change
+                self.assertIn("# Unsaved change", text.get('1.0', 'end-1c'))
+            finally:
+                iomenu.messagebox.askokcancel = orig_askokcancel
+        finally:
+            os.unlink(temp_filename)
+
+    def test_reload_with_unsaved_changes_confirm(self):
+        # Test reload with unsaved changes and user confirms
+        import tempfile
+        import os
+
+        io = self.io
+        text = io.editwin.text
+
+        # Create a temporary file
+        with tempfile.NamedTemporaryFile(mode='w', delete=False, suffix='.py') as f:
+            f.write("# Original content\n")
+            temp_filename = f.name
+
+        try:
+            # Load the file
+            io.loadfile(temp_filename)
+
+            # Make unsaved changes
+            text.insert('end-1c', "\n# Unsaved change")
+            io.set_saved(False)
+
+            # Mock askokcancel to return True (confirm)
+            orig_askokcancel = iomenu.messagebox.askokcancel
+            iomenu.messagebox.askokcancel = lambda *args, **kwargs: True
+
+            try:
+                result = io.reload(None)
+                self.assertEqual(result, "break")
+                # Content should be reverted to original
+                self.assertEqual(text.get('1.0', 'end-1c'), "# Original content\n")
+            finally:
+                iomenu.messagebox.askokcancel = orig_askokcancel
+        finally:
+            os.unlink(temp_filename)
+
 
 def _extension_in_filetypes(extension):
     return any(

Lib/idlelib/iomenu.py

@@ -31,6 +31,7 @@ def __init__(self, editwin):
                                           self.save_as)
         self.__id_savecopy = self.text.bind("<<save-copy-of-window-as-file>>",
                                             self.save_a_copy)
+        self.__id_reload = self.text.bind("<<reload-window>>", self.reload)
         self.fileencoding = 'utf-8'
         self.__id_print = self.text.bind("<<print-window>>", self.print_window)
 
@@ -40,6 +41,7 @@ def close(self):
         self.text.unbind("<<save-window>>", self.__id_save)
         self.text.unbind("<<save-window-as-file>>",self.__id_saveas)
         self.text.unbind("<<save-copy-of-window-as-file>>", self.__id_savecopy)
+        self.text.unbind("<<reload-window>>", self.__id_reload)
         self.text.unbind("<<print-window>>", self.__id_print)
         # Break cycles
         self.editwin = None
@@ -237,6 +239,49 @@ def save_a_copy(self, event):
         self.updaterecentfileslist(filename)
         return "break"
 
+    def reload(self, event):
+        """Reload the file from disk, discarding any unsaved changes.
+
+        If the file has unsaved changes, ask the user to confirm.
+        """
+        if not self.filename:
+            messagebox.showinfo(
+                "No File",
+                "This window has no associated file to reload.",
+                parent=self.text)
+            self.text.focus_set()
+            return "break"
+
+        if not self.get_saved():
+            confirm = messagebox.askokcancel(
+                title="Reload File",
+                message=f"Discard changes to {self.filename}?",
+                default=messagebox.CANCEL,
+                parent=self.text)
+            if not confirm:
+                self.text.focus_set()
+                return "break"
+
+        # Save cursor position
+        insert_pos = self.text.index("insert")
+        yview_pos = self.text.yview()
+
+        # Reload the file
+        if self.loadfile(self.filename):
+            # Try to restore cursor position if the file still has that line
+            try:
+                self.text.mark_set("insert", insert_pos)
+                self.text.see("insert")
+                # Restore vertical scroll position
+                self.text.yview_moveto(yview_pos[0])
+            except Exception:
+                # If position doesn't exist anymore, go to top
+                self.text.mark_set("insert", "1.0")
+                self.text.see("insert")
+
+        self.text.focus_set()
+        return "break"
+
     def writefile(self, filename):
         text = self.fixnewlines()
         chars = self.encode(text)

Lib/idlelib/mainmenu.py

@@ -31,6 +31,7 @@
    ('_Save', '<<save-window>>'),
    ('Save _As...', '<<save-window-as-file>>'),
    ('Save Cop_y As...', '<<save-copy-of-window-as-file>>'),
+   ('Re_load from Disk', '<<reload-window>>'),
    None,
    ('Prin_t Window', '<<print-window>>'),
    None,

Misc/NEWS.d/next/IDLE/2025-11-14-20-58-55.gh-issue-44968.rL9dK3.rst

@@ -0,0 +1,4 @@
+Add "Reload from Disk" menu item to IDLE's File menu. This allows users to
+easily reload a file from disk, discarding any unsaved changes in the editor.
+The feature is particularly useful when working with version control systems
+or when external tools modify files. Patch by ashm-dev.