Added always_show_hint setting

Fixed issue where flag names weren't always sorted correctly in argparse tab completion

CHANGELOG.md

@@ -1,3 +1,11 @@
+## 1.4.0 (TBD, 2020)
+* Enhancements
+    * Added user-settable option called `always_show_hint`. If True, then tab completion hints will always
+    display even when tab completion suggestions print. Arguments whose help or hint text is suppressed will
+    not display hints even when this setting is True.
+* Bug Fixes
+    * Fixed issue where flag names weren't always sorted correctly in argparse tab completion
+
 ## 1.3.9 (September 03, 2020)
 * Breaking Changes
     * `CommandSet.on_unregister()` is now called as first step in unregistering a `CommandSet` and not

README.md

@@ -322,6 +322,7 @@ example/transcript_regex.txt:
 # regexes on prompts just make the trailing space obvious
 (Cmd) set
 allow_style: '/(Terminal|Always|Never)/'
+always_show_hint: False
 debug: False
 echo: False
 editor: /.*?/

cmd2/argparse_completer.py

@@ -35,6 +35,22 @@
 ARG_TOKENS = 'arg_tokens'
 
 
+# noinspection PyProtectedMember
+def _build_hint(parser: argparse.ArgumentParser, arg_action: argparse.Action) -> str:
+    """Build tab completion hint for a given argument"""
+    # Check if hinting is disabled for this argument
+    suppress_hint = getattr(arg_action, ATTR_SUPPRESS_TAB_HINT, False)
+    if suppress_hint or arg_action.help == argparse.SUPPRESS:
+        return ''
+    else:
+        # Use the parser's help formatter to display just this action's help text
+        formatter = parser._get_formatter()
+        formatter.start_section("Hint")
+        formatter.add_argument(arg_action)
+        formatter.end_section()
+        return formatter.format_help()
+
+
 def _single_prefix_char(token: str, parser: argparse.ArgumentParser) -> bool:
     """Returns if a token is just a single flag prefix character"""
     return len(token) == 1 and token[0] in parser.prefix_chars
@@ -115,7 +131,6 @@ def __init__(self, flag_arg_state: _ArgumentState) -> None:
         super().__init__(error)
 
 
-# noinspection PyProtectedMember
 class _NoResultsError(CompletionError):
     def __init__(self, parser: argparse.ArgumentParser, arg_action: argparse.Action) -> None:
         """
@@ -124,19 +139,8 @@ def __init__(self, parser: argparse.ArgumentParser, arg_action: argparse.Action)
         :param parser: ArgumentParser instance which owns the action being tab completed
         :param arg_action: action being tab completed
         """
-        # Check if hinting is disabled
-        suppress_hint = getattr(arg_action, ATTR_SUPPRESS_TAB_HINT, False)
-        if suppress_hint or arg_action.help == argparse.SUPPRESS:
-            hint_str = ''
-        else:
-            # Use the parser's help formatter to print just this action's help text
-            formatter = parser._get_formatter()
-            formatter.start_section("Hint")
-            formatter.add_argument(arg_action)
-            formatter.end_section()
-            hint_str = formatter.format_help()
         # Set apply_style to False because we don't want hints to look like errors
-        super().__init__(hint_str, apply_style=False)
+        super().__init__(_build_hint(parser, arg_action), apply_style=False)
 
 
 # noinspection PyProtectedMember
@@ -411,6 +415,7 @@ def update_mutex_groups(arg_action: argparse.Action) -> None:
 
             # If we have results, then return them
             if completion_results:
+                self._cmd2_app.completion_hint = _build_hint(self._parser, flag_arg_state.action)
                 return completion_results
 
             # Otherwise, print a hint if the flag isn't finished or text isn't possibly the start of a flag
@@ -432,6 +437,7 @@ def update_mutex_groups(arg_action: argparse.Action) -> None:
 
             # If we have results, then return them
             if completion_results:
+                self._cmd2_app.completion_hint = _build_hint(self._parser, pos_arg_state.action)
                 return completion_results
 
             # Otherwise, print a hint if text isn't possibly the start of a flag
@@ -566,12 +572,21 @@ def _complete_for_arg(self, arg_state: _ArgumentState,
         """
         # Check if the arg provides choices to the user
         if arg_state.action.choices is not None:
-            arg_choices = arg_state.action.choices
+            arg_choices = list(arg_state.action.choices)
+            if not arg_choices:
+                return []
+
+            # If these choices are numbers, then sort them now
+            if all(isinstance(x, numbers.Number) for x in arg_choices):
+                arg_choices.sort()
+                self._cmd2_app.matches_sorted = True
+
+            # Since choices can be various types, convert them all to strings
+            arg_choices = [str(x) for x in arg_choices]
         else:
             arg_choices = getattr(arg_state.action, ATTR_CHOICES_CALLABLE, None)
-
-        if arg_choices is None:
-            return []
+            if arg_choices is None:
+                return []
 
         # If we are going to call a completer/choices function, then set up the common arguments
         args = []
@@ -612,24 +627,17 @@ def _complete_for_arg(self, arg_state: _ArgumentState,
             if isinstance(arg_choices, ChoicesCallable) and not arg_choices.is_completer:
                 arg_choices = arg_choices.to_call(*args, **kwargs)
 
-            # Since arg_choices can be any iterable type, convert to a list
-            arg_choices = list(arg_choices)
-
-            # If these choices are numbers, and have not yet been sorted, then sort them now
-            if not self._cmd2_app.matches_sorted and all(isinstance(x, numbers.Number) for x in arg_choices):
-                arg_choices.sort()
-                self._cmd2_app.matches_sorted = True
-
-            # Since choices can be various types like int, we must convert them to strings
-            for index, choice in enumerate(arg_choices):
-                if not isinstance(choice, str):
-                    arg_choices[index] = str(choice)
-
             # Filter out arguments we already used
             used_values = consumed_arg_values.get(arg_state.action.dest, [])
             arg_choices = [choice for choice in arg_choices if choice not in used_values]
 
             # Do tab completion on the choices
             results = basic_complete(text, line, begidx, endidx, arg_choices)
 
+        if not results:
+            # Reset the value for matches_sorted. This is because completion of flag names
+            # may still be attempted after we return and they haven't been sorted yet.
+            self._cmd2_app.matches_sorted = False
+            return []
+
         return self._format_completions(arg_state, results)

cmd2/cmd2.py

@@ -208,6 +208,7 @@ def __init__(self, completekey: str = 'tab', stdin=None, stdout=None, *,
         self.allow_redirection = allow_redirection  # Security setting to prevent redirection of stdout
 
         # Attributes which ARE dynamically settable via the set command at runtime
+        self.always_show_hint = False
         self.debug = False
         self.echo = False
         self.editor = Cmd.DEFAULT_EDITOR
@@ -375,17 +376,21 @@ def __init__(self, completekey: str = 'tab', stdin=None, stdout=None, *,
         # will be added if there is an unmatched opening quote
         self.allow_closing_quote = True
 
-        # An optional header that prints above the tab completion suggestions
+        # An optional hint which prints above tab completion suggestions
+        self.completion_hint = ''
+
+        # Header which prints above CompletionItem tables
         self.completion_header = ''
 
         # Used by complete() for readline tab completion
         self.completion_matches = []
 
-        # Use this list if you are completing strings that contain a common delimiter and you only want to
-        # display the final portion of the matches as the tab completion suggestions. The full matches
-        # still must be returned from your completer function. For an example, look at path_complete()
-        # which uses this to show only the basename of paths as the suggestions. delimiter_complete() also
-        # populates this list.
+        # Use this list if you need to display tab completion suggestions that are different than the actual text
+        # of the matches. For instance, if you are completing strings that contain a common delimiter and you only
+        # want to display the final portion of the matches as the tab completion suggestions. The full matches
+        # still must be returned from your completer function. For an example, look at path_complete() which
+        # uses this to show only the basename of paths as the suggestions. delimiter_complete() also populates
+        # this list.
         self.display_matches = []
 
         # Used by functions like path_complete() and delimiter_complete() to properly
@@ -788,6 +793,8 @@ def build_settables(self):
                                                         ansi.STYLE_NEVER),
                                    choices=[ansi.STYLE_TERMINAL, ansi.STYLE_ALWAYS, ansi.STYLE_NEVER]))
 
+        self.add_settable(Settable('always_show_hint', bool,
+                                   'Display tab completion hint even when completion suggestions print'))
         self.add_settable(Settable('debug', bool, "Show full traceback on exception"))
         self.add_settable(Settable('echo', bool, "Echo command issued into output"))
         self.add_settable(Settable('editor', str, "Program used by 'edit'"))
@@ -984,6 +991,7 @@ def _reset_completion_defaults(self) -> None:
         """
         self.allow_appended_space = True
         self.allow_closing_quote = True
+        self.completion_hint = ''
         self.completion_header = ''
         self.completion_matches = []
         self.display_matches = []
@@ -1479,6 +1487,22 @@ def _pad_matches_to_display(matches_to_display: List[str]) -> Tuple[List[str], i
 
         return [cur_match + padding for cur_match in matches_to_display], len(padding)
 
+    def _build_completion_metadata_string(self) -> str:  # pragma: no cover
+        """Build completion metadata string which can contain a hint and CompletionItem table header"""
+        metadata = ''
+
+        # Add hint if one exists and we are supposed to display it
+        if self.always_show_hint and self.completion_hint:
+            metadata += '\n' + self.completion_hint
+
+        # Add table header if one exists
+        if self.completion_header:
+            if not metadata:
+                metadata += '\n'
+            metadata += '\n' + self.completion_header
+
+        return metadata
+
     def _display_matches_gnu_readline(self, substitution: str, matches: List[str],
                                       longest_match_length: int) -> None:  # pragma: no cover
         """Prints a match list using GNU readline's rl_display_match_list()
@@ -1523,9 +1547,8 @@ def _display_matches_gnu_readline(self, substitution: str, matches: List[str],
             strings_array[1:-1] = encoded_matches
             strings_array[-1] = None
 
-            # Print the header if one exists
-            if self.completion_header:
-                sys.stdout.write('\n\n' + self.completion_header)
+            # Print any metadata like a hint or table header
+            sys.stdout.write(self._build_completion_metadata_string())
 
             # Call readline's display function
             # rl_display_match_list(strings_array, number of completion matches, longest match length)
@@ -1551,10 +1574,8 @@ def _display_matches_pyreadline(self, matches: List[str]) -> None:  # pragma: no
             # Add padding for visual appeal
             matches_to_display, _ = self._pad_matches_to_display(matches_to_display)
 
-            # Print the header if one exists
-            if self.completion_header:
-                # noinspection PyUnresolvedReferences
-                readline.rl.mode.console.write('\n\n' + self.completion_header)
+            # Print any metadata like a hint or table header
+            readline.rl.mode.console.write(sys.stdout.write(self._build_completion_metadata_string()))
 
             # Display matches using actual display function. This also redraws the prompt and line.
             orig_pyreadline_display(matches_to_display)
@@ -3317,7 +3338,7 @@ def complete_set_value(self, text: str, line: str, begidx: int, endidx: int,
     # Create the parser for the set command
     set_parser = DEFAULT_ARGUMENT_PARSER(parents=[set_parser_parent])
     set_parser.add_argument('value', nargs=argparse.OPTIONAL, help='new value for settable',
-                            completer_method=complete_set_value)
+                            completer_method=complete_set_value, suppress_tab_hint=True)
 
     # Preserve quotes so users can pass in quoted empty strings and flags (e.g. -h) as the value
     @with_argparser(set_parser, preserve_quotes=True)

examples/transcripts/transcript_regex.txt

@@ -4,6 +4,7 @@
 # regexes on prompts just make the trailing space obvious
 (Cmd) set
 allow_style: '/(Terminal|Always|Never)/'
+always_show_hint: False
 debug: False
 echo: False
 editor: /.*?/

tests/conftest.py

@@ -93,6 +93,7 @@ def verify_help_text(cmd2_app: cmd2.Cmd,
 
 # Output from the show command with default settings
 SHOW_TXT = """allow_style: 'Terminal'
+always_show_hint: False
 debug: False
 echo: False
 editor: 'vim'
@@ -104,6 +105,7 @@ def verify_help_text(cmd2_app: cmd2.Cmd,
 
 SHOW_LONG = """
 allow_style: 'Terminal'   # Allow ANSI text style sequences in output (valid values: Terminal, Always, Never)
+always_show_hint: False   # Display tab completion hint even when completion suggestions print
 debug: False              # Show full traceback on exception
 echo: False               # Echo command issued into output
 editor: 'vim'             # Program used by 'edit'