bpo-33046: An IDLE option to strip trailing whitespace on save

Lib/idlelib/config-main.def

@@ -67,6 +67,7 @@ font-size= 10
 font-bold= 0
 encoding= none
 line-numbers-default= 0
+strip-trailing-whitespace-on-save= 1
 
 [PyShell]
 auto-squeeze-min-lines= 50

Lib/idlelib/configdialog.py

@@ -1848,6 +1848,9 @@ class GenPage(Frame):
                 frame_context: Frame
                     context_title: Label
                     (*)context_int: Entry - context_lines
+                frame_strip_trailing_space_save: Frame
+                    strip_trailing_space_save_title: Label
+                    (*)strip_trailing_space_save_bool: Checkbutton - strip_trailing_space_save
             frame_shell: LabelFrame
                 frame_auto_squeeze_min_lines: Frame
                     auto_squeeze_min_lines_title: Label
@@ -1891,6 +1894,9 @@ class GenPage(Frame):
                 ('main', 'EditorWindow', 'line-numbers-default'))
         self.context_lines = tracers.add(
                 StringVar(self), ('extensions', 'CodeContext', 'maxlines'))
+        self.strip_trailing_space_save = tracers.add(
+                BooleanVar(self),
+                ('main', 'EditorWindow', 'strip-trailing-whitespace-on-save'))
 
         # Create widgets:
         # Section frames.
@@ -1987,6 +1993,14 @@ class GenPage(Frame):
                 validatecommand=self.digits_only, validate='key',
         )
 
+        frame_strip_trailing_space_save = Frame(frame_editor, borderwidth=0)
+        strip_trailing_space_save_title = Label(
+                frame_strip_trailing_space_save,
+                text='Strip Trailing Whitespace on Save')
+        self.strip_trailing_space_save_bool = Checkbutton(
+                frame_strip_trailing_space_save,
+                variable=self.strip_trailing_space_save, width=1)
+
         # Frame_shell.
         frame_auto_squeeze_min_lines = Frame(frame_shell, borderwidth=0)
         auto_squeeze_min_lines_title = Label(frame_auto_squeeze_min_lines,
@@ -2069,6 +2083,11 @@ class GenPage(Frame):
         frame_context.pack(side=TOP, padx=5, pady=0, fill=X)
         context_title.pack(side=LEFT, anchor=W, padx=5, pady=5)
         self.context_int.pack(side=TOP, padx=5, pady=5)
+        # frame_strip_trailing_space_save.
+        frame_strip_trailing_space_save.pack(side=TOP, padx=5, pady=0, fill=X)
+        strip_trailing_space_save_title.pack(
+                side=LEFT, anchor=W,padx=5, pady=5)
+        self.strip_trailing_space_save_bool.pack(side=LEFT, padx=5, pady=5)
 
         # frame_auto_squeeze_min_lines
         frame_auto_squeeze_min_lines.pack(side=TOP, padx=5, pady=0, fill=X)
@@ -2113,6 +2132,9 @@ class GenPage(Frame):
                 'main', 'EditorWindow', 'line-numbers-default', type='bool'))
         self.context_lines.set(idleConf.GetOption(
                 'extensions', 'CodeContext', 'maxlines', type='int'))
+        self.strip_trailing_space_save.set(
+                idleConf.GetOption('main', 'EditorWindow',
+                    'strip-trailing-whitespace-on-save', type='bool'))
 
         # Set variables for shell windows.
         self.auto_squeeze_min_lines.set(idleConf.GetOption(

Lib/idlelib/iomenu.py

@@ -371,6 +371,11 @@ class IOBinding:
         return "break"
 
     def writefile(self, filename):
+        strip = idleConf.GetOption(
+                'main', 'EditorWindow',
+                'strip-trailing-whitespace-on-save', type='bool')
+        if strip:
+            self.editwin.Rstrip(self.editwin).do_rstrip()
         text = self.fixnewlines()
         chars = self.encode(text)
         try:

Misc/NEWS.d/next/IDLE/2019-11-16-23-54-30.bpo-33046.VMwGaW.rst

@@ -0,0 +1,2 @@
+Add an option to IDLE to automatically strip trailing whitespace when saving
+a file.  The option is enabled by default.