f-strings and other various syntax upgrades after dropping 3.7

face/__init__.py

@@ -1,4 +1,3 @@
-
 from face.parser import (Flag,
                          FlagDisplay,
                          ERROR,

face/command.py

@@ -1,6 +1,3 @@
-
-from __future__ import print_function
-
 import sys
 from collections import OrderedDict
 
@@ -97,7 +94,7 @@ def __init__(self, func, name=None, doc=None, **kwargs):
             doc = _docstring_to_doc(func)
 
         # TODO: default posargs if none by inspecting func
-        super(Command, self).__init__(name, doc,
+        super().__init__(name, doc,
                                       flags=kwargs.pop('flags', None),
                                       posargs=kwargs.pop('posargs', None),
                                       post_posargs=kwargs.pop('post_posargs', None),
@@ -119,7 +116,7 @@ def __init__(self, func, name=None, doc=None, **kwargs):
             self.add_middleware(mw)
 
         if kwargs:
-            raise TypeError('unexpected keyword arguments: %r' % sorted(kwargs.keys()))
+            raise TypeError(f'unexpected keyword arguments: {sorted(kwargs.keys())!r}')
 
         if _help:
             if _help.flag:
@@ -178,7 +175,7 @@ def add(self, *a, **kw):
         flag = a[0]
         if not isinstance(flag, Flag):
             flag = Flag(*a, **kw)  # attempt to construct a Flag from arguments
-        super(Command, self).add(flag)
+        super().add(flag)
 
         return flag
 
@@ -191,9 +188,9 @@ def add_command(self, subcmd):
         conflicting middlewares or subcommand names.
         """
         if not isinstance(subcmd, Command):
-            raise TypeError('expected Command instance, not: %r' % subcmd)
+            raise TypeError(f'expected Command instance, not: {subcmd!r}')
         self_mw = self._path_mw_map[()]
-        super(Command, self).add(subcmd)
+        super().add(subcmd)
         # map in new functions
         for path in self.subprs_map:
             if path not in self._path_func_map:
@@ -226,7 +223,7 @@ def get_flag_map(self, path=(), with_hidden=True):
         the flag map to just the flags used by the endpoint at the
         associated subcommand *path*.
         """
-        flag_map = super(Command, self).get_flag_map(path=path, with_hidden=with_hidden)
+        flag_map = super().get_flag_map(path=path, with_hidden=with_hidden)
         dep_names = self.get_dep_names(path)
         if 'args_' in dep_names or 'flags_' in dep_names:
             # the argument parse result and flag dict both capture
@@ -315,7 +312,7 @@ def prepare(self, paths=None):
             try:
                 wrapped = get_middleware_chain(mws, func, provides)
             except NameError as ne:
-                ne.args = (ne.args[0] + ' (in path: %r)' % (path,),)
+                ne.args = (ne.args[0] + f' (in path: {path!r})',)
                 raise
 
             self._path_wrapped_map[path] = wrapped
@@ -352,8 +349,7 @@ def run(self, argv=None, extras=None, print_error=None):
         if print_error is None or print_error is True:
             print_error = default_print_error
         elif print_error and not callable(print_error):
-            raise TypeError('expected callable for print_error, not %r'
-                            % print_error)
+            raise TypeError(f'expected callable for print_error, not {print_error!r}')
 
         kwargs = dict(extras) if extras else {}
         kwargs['print_error_'] = print_error  # TODO: print_error_ in builtin provides?

face/errors.py

@@ -1,4 +1,3 @@
-
 from boltons.iterutils import unique
 
 import face.utils
@@ -50,8 +49,7 @@ def from_parse(cls, cmd_flag_map, flag_name):
         # TODO: add edit distance calculation
         valid_flags = unique([face.utils.format_flag_label(flag) for flag in
                               cmd_flag_map.values() if not flag.display.hidden])
-        msg = ('unknown flag "%s", choose from: %s'
-               % (flag_name, ', '.join(valid_flags)))
+        msg = f"unknown flag \"{flag_name}\", choose from: {', '.join(valid_flags)}"
         return cls(msg)
 
 
@@ -63,7 +61,7 @@ class InvalidFlagArgument(ArgumentParseError):
     @classmethod
     def from_parse(cls, cmd_flag_map, flag, arg, exc=None):
         if arg is None:
-            return cls('expected argument for flag %s' % flag.name)
+            return cls(f'expected argument for flag {flag.name}')
 
         val_parser = flag.parse_as
         vp_label = getattr(val_parser, 'display_name', face.utils.FRIENDLY_TYPE_NAMES.get(val_parser))
@@ -76,7 +74,7 @@ def from_parse(cls, cmd_flag_map, flag, arg, exc=None):
 
         if exc:
             # TODO: put this behind a verbose flag?
-            msg += ' (got error: %r)' % exc
+            msg += f' (got error: {exc!r})'
         if arg.startswith('-'):
             msg += '. (Did you forget to pass an argument?)'
 
@@ -105,8 +103,7 @@ def from_parse(cls, cmd_flag_map, parsed_flag_map, missing_flag_names):
         for flag_name in flag_names:
             flag = cmd_flag_map[flag_name]
             labels.append(face.utils.format_flag_label(flag))
-        msg = ('missing required arguments for flags: %s'
-               % ', '.join(sorted(labels)))
+        msg = f"missing required arguments for flags: {', '.join(sorted(labels))}"
         return cls(msg)
 
 
@@ -118,10 +115,9 @@ class DuplicateFlag(ArgumentParseError):
     def from_parse(cls, flag, arg_val_list):
         avl_text = ', '.join([repr(v) for v in arg_val_list])
         if callable(flag.parse_as):
-            msg = ('more than one value was passed for flag "%s": %s'
-                   % (flag.name, avl_text))
+            msg = f'more than one value was passed for flag "{flag.name}": {avl_text}'
         else:
-            msg = ('flag "%s" was used multiple times, but can be used only once' % flag.name)
+            msg = f'flag "{flag.name}" was used multiple times, but can be used only once'
         return cls(msg)
 
 

face/helpers.py

@@ -1,4 +1,3 @@
-
 import os
 import sys
 import array
@@ -147,7 +146,7 @@ def get_stout_layout(labels, indent, sep, width=None, max_width=DEFAULT_MAX_WIDT
 }
 
 
-class StoutHelpFormatter(object):
+class StoutHelpFormatter:
     """This formatter takes :class:`Parser` and :class:`Command` instances
     and generates help text. The output style is inspired by, but not
     the same as, argparse's automatic help formatting.
@@ -215,7 +214,7 @@ def __init__(self, **kwargs):
         for key, val in self.default_context.items():
             self.ctx[key] = kwargs.pop(key, val)
         if kwargs:
-            raise TypeError('unexpected formatter arguments: %r' % list(kwargs.keys()))
+            raise TypeError(f'unexpected formatter arguments: {list(kwargs.keys())!r}')
 
     def _get_layout(self, labels):
         ctx = self.ctx
@@ -362,7 +361,7 @@ class AiryHelpFormatter(object):
 '''
 
 
-class HelpHandler(object):
+class HelpHandler:
     """The HelpHandler is a one-stop object for that all-important CLI
     feature: automatic help generation. It ties together the actual
     help handler with the optional flag and subcommand such that it
@@ -402,11 +401,11 @@ def __init__(self, flag=DEFAULT_HELP_FLAG, subcmd=None,
         self.subcmd = subcmd
         self.func = func if func is not None else self.default_help_func
         if not callable(self.func):
-            raise TypeError('expected help handler func to be callable, not %r' % func)
+            raise TypeError(f'expected help handler func to be callable, not {func!r}')
 
         self.formatter = formatter
         if not formatter:
-            raise TypeError('expected Formatter type or instance, not: %r' % formatter)
+            raise TypeError(f'expected Formatter type or instance, not: {formatter!r}')
         if isinstance(formatter, type):
             self.formatter = formatter(**formatter_kwargs)
         elif formatter_kwargs:

face/middleware.py

@@ -196,10 +196,10 @@ def face_middleware(func=None, **kwargs):
     if flags:
         for flag in flags:
             if not isinstance(flag, Flag):
-                raise TypeError('expected Flag object, not: %r' % flag)
+                raise TypeError(f'expected Flag object, not: {flag!r}')
     optional = kwargs.pop('optional', False)
     if kwargs:
-        raise TypeError('unexpected keyword arguments: %r' % kwargs.keys())
+        raise TypeError(f'unexpected keyword arguments: {kwargs.keys()!r}')
 
     def decorate_face_middleware(func):
         check_middleware(func, provides=provides)
@@ -239,13 +239,13 @@ def get_middleware_chain(middlewares, innermost, preprovided):
     if INNER_NAME in get_arg_names(innermost):
         raise NameError(_inner_exc_msg % (INNER_NAME, innermost))
 
-    mw_builtins = set(preprovided) - set([INNER_NAME])
+    mw_builtins = set(preprovided) - {INNER_NAME}
     mw_provides = [list(mw._face_provides) for mw in middlewares]
 
     mw_chain, mw_chain_args, mw_unres = make_chain(middlewares, mw_provides, innermost, mw_builtins, INNER_NAME)
 
     if mw_unres:
-        msg = "unresolved middleware or handler arguments: %r" % sorted(mw_unres)
+        msg = f"unresolved middleware or handler arguments: {sorted(mw_unres)!r}"
         avail_unres = mw_unres & (mw_builtins | set(sum(mw_provides, [])))
         if avail_unres:
             msg += (' (%r provided but not resolvable, check middleware order.)'
@@ -261,7 +261,7 @@ def check_middleware(func, provides=None):
     raises :exc:`TypeError` if any issues are found.
     """
     if not callable(func):
-        raise TypeError('expected middleware %r to be a function' % func)
+        raise TypeError(f'expected middleware {func!r} to be a function')
     fb = get_fb(func)
     # TODO: this currently gives __main__abc instead of __main__.abc
     func_label = ''.join(get_callable_labels(func))