Refactor write_config_py

qutebrowser/config/configcommands.py

@@ -275,5 +275,6 @@ class ConfigCommands:
             bindings = dict(self._config.get_obj('bindings.commands'))
             commented = False
 
-        configfiles.write_config_py(filename, options, bindings,
-                                    commented=commented)
+        writer = configfiles.ConfigPyWriter(options, bindings,
+                                            commented=commented)
+        writer.write(filename)

qutebrowser/config/configfiles.py

@@ -245,59 +245,94 @@ class ConfigAPI:
             self._keyconfig.unbind(key, mode=mode)
 
 
-def write_config_py(filename, options, bindings, *, commented):
-    """Write a config.py file from given values."""
-    c = '#' if commented else ''
-    cs = '# ' if commented else ''
-    with open(filename, 'w', encoding='utf-8') as f:
-        f.write(c + "# Autogenerated config.py\n")
-        f.write(c + "# Documentation:\n")
-        f.write(c + "#   qute://help/configuring.html\n")
-        f.write(c + "#   qute://help/settings.html\n\n")
-        if commented:
+class ConfigPyWriter:
+
+    """Writer for config.py files from given settings."""
+
+    def __init__(self, options, bindings, *, commented):
+        self._options = options
+        self._bindings = bindings
+        self._commented = commented
+
+    def write(self, filename):
+        """Write the config to the given file."""
+        with open(filename, 'w', encoding='utf-8') as f:
+            f.write('\n'.join(self._gen_text()))
+
+    def _line(self, line):
+        """Get an (optionally commented) line."""
+        if self._commented:
+            if line.startswith('#'):
+                return '#' + line
+            else:
+                return '# ' + line
+        else:
+            return line
+
+    def _gen_text(self):
+        """Generate a config.py with the given settings/bindings.
+
+        Yields individual lines.
+        """
+        yield from self._gen_header()
+        yield from self._gen_options()
+        yield from self._gen_bindings()
+
+    def _gen_header(self):
+        """Generate the intiial header of the config."""
+        yield self._line("# Autogenerated config.py")
+        yield self._line("# Documentation:")
+        yield self._line("#   qute://help/configuring.html")
+        yield self._line("#   qute://help/settings.html\n")
+        if self._commented:
             # When generated from an autoconfig.yml with commented=False,
             # we don't want to load that autoconfig.yml anymore.
-            f.write("## This is here so configs done via the GUI are still "
-                    "loaded.\n")
-            f.write("## Remove it to not load settings done via the GUI.\n")
-            f.write("config.load_autoconfig()\n\n")
+            yield self._line("# This is here so configs done via the GUI are "
+                             "still loaded.")
+            yield self._line("# Remove it to not load settings done via the "
+                             "GUI.")
+            yield self._line("config.load_autoconfig()\n")
         else:
-            f.write("# Uncomment this to still load settings configured via "
-                    "autoconfig.yml\n")
-            f.write("# config.load_autoconfig()\n\n")
+            yield self._line("# Uncomment this to still load settings "
+                             "configured via autoconfig.yml")
+            yield self._line("# config.load_autoconfig()\n")
 
-        for opt, value in options:
+    def _gen_options(self):
+        """Generate the options part of the config."""
+        for opt, value in self._options:
             if opt.name in ['bindings.commands', 'bindings.default']:
                 continue
 
             for line in textwrap.wrap(opt.description):
-                f.write(c + "# {}\n".format(line))
+                yield self._line("# {}".format(line))
 
-            f.write(c + "# Type: {}\n".format(opt.typ.get_name()))
+            yield self._line("# Type: {}".format(opt.typ.get_name()))
 
             valid_values = opt.typ.get_valid_values()
             if valid_values is not None and valid_values.generate_docs:
-                f.write(c + "# Valid values:\n")
+                yield self._line("# Valid values:")
                 for val in valid_values:
                     try:
                         desc = valid_values.descriptions[val]
-                        f.write(c + "#   - {}: {}".format(val, desc) + "\n")
+                        yield self._line("#   - {}: {}".format(val, desc))
                     except KeyError:
-                        f.write(c + "#   - {}".format(val) + "\n")
+                        yield self._line("#   - {}".format(val))
 
-            f.write(cs + 'c.{} = {!r}\n\n'.format(opt.name, value))
+            yield self._line('c.{} = {!r}\n'.format(opt.name, value))
 
-        normal_bindings = bindings.pop('normal', {})
+    def _gen_bindings(self):
+        """Generate the bindings part of the config."""
+        normal_bindings = self._bindings.pop('normal', {})
         if normal_bindings:
-            f.write(c + '# Bindings for normal mode\n')
+            yield self._line('# Bindings for normal mode')
         for key, command in sorted(normal_bindings.items()):
-            f.write(cs + 'config.bind({!r}, {!r})\n'.format(key, command))
+            yield self._line('config.bind({!r}, {!r})'.format(key, command))
 
-        for mode, mode_bindings in sorted(bindings.items()):
-            f.write('\n')
-            f.write(c + '# Bindings for {} mode\n'.format(mode))
+        for mode, mode_bindings in sorted(self._bindings.items()):
+            yield ''
+            yield self._line('# Bindings for {} mode'.format(mode))
             for key, command in sorted(mode_bindings.items()):
-                f.write(cs + 'config.bind({!r}, {!r}, mode={!r})\n'.format(
+                yield self._line('config.bind({!r}, {!r}, mode={!r})'.format(
                     key, command, mode))