Merge pull request #1417 from Textualize/key-refactor

keys refactor

CHANGELOG.md

@@ -5,6 +5,7 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+
 ## [0.8.0] - Unreleased
 
 ### Fixed
@@ -18,10 +19,14 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - Added `textual.actions.SkipAction` exception which can be raised from an action to allow parents to process bindings.
 - Added `textual keys` preview.
+- Added ability to bind to a character in addition to key name. i.e. you can bind to "." or "full_stop".
+- Added TextLog.shrink attribute to allow renderable to reduce in size to fit width.
 
 ### Changed
 
-- Moved Ctrl+C, tab, and shift+tab to App BINDINGS
+- Deprecated `PRIORITY_BINDINGS` class variable.
+- Renamed `char` to `character` on Key event.
+- Renamed `key_name` to `name` on Key event.
 - Queries/`walk_children` no longer includes self in results by default https://github.com/Textualize/textual/pull/1416
 
 ## [0.7.0] - 2022-12-17

docs/guide/actions.md

@@ -90,6 +90,8 @@ Textual will run actions bound to keys. The following example adds key [bindings
 
 If you run this example, you can change the background by pressing keys in addition to clicking links.
 
+See the previous section on [input](./input.md#bindings) for more information on bindings.
+
 ## Namespaces
 
 Textual will look for action methods in the class where they are defined (App, Screen, or Widget). If we were to create a [custom widget](./widgets.md#custom-widgets) it can have its own set of actions.
@@ -124,37 +126,9 @@ In the previous example if you wanted a link to set the background on the app ra
 
 Textual supports the following builtin actions which are defined on the app.
 
-
+- [action_bell][textual.app.App.action_bell]
-### Bell
+- [action_push_screen][textual.app.App.action_push_screen]
-
+- [action_pop_screen][textual.app.App.action_pop_screen]
-::: textual.app.App.action_bell
+- [action_switch_screen][textual.app.App.action_switch_screen]
-    options:
+- [action_screenshot][textual.app.App.action_screenshot]
-        show_root_heading: false
+- [action_toggle_dark][textual.app.App.action_toggle_dark]
-
-### Push screen
-
-::: textual.app.App.action_push_screen
-
-
-### Pop screen
-
-::: textual.app.App.action_pop_screen
-
-
-### Screenshot
-
-::: textual.app.App.action_screenshot
-
-
-### Switch screen
-
-::: textual.app.App.action_switch_screen
-
-
-### Toggle_dark
-
-::: textual.app.App.action_toggle_dark
-
-### Quit
-
-::: textual.app.App.action_quit

docs/guide/input.md

@@ -10,7 +10,7 @@ This chapter will discuss how to make your app respond to input in the form of k
 
 ## Keyboard input
 
-The most fundamental way to receive input is via [Key](./events/key) events. Let's write an app to show key events as you type.
+The most fundamental way to receive input is via [Key][textual.events.Key] events which are sent to your app when the user presses a key. Let's write an app to show key events as you type.
 
 === "key01.py"
 
@@ -23,25 +23,52 @@ The most fundamental way to receive input is via [Key](./events/key) events. Let
     ```{.textual path="docs/examples/guide/input/key01.py", press="T,e,x,t,u,a,l,!,_"}
     ```
 
-Note the key event handler on the app which logs all key events. If you press any key it will show up on the screen.
+When you press a key, the app will receive the event and write it to a [TextLog](../widgets/text_log.md) widget. Try pressing a few keys to see what happens.
 
-### Attributes
+!!! tip
 
-There are two main attributes on a key event. The `key` attribute is the _name_ of the key which may be a single character, or a longer identifier. Textual ensures that the `key` attribute could always be used in a method name.
+    For a more feature feature rich version of this example, run `textual keys` from the command line.
 
-Key events also contain a `char` attribute which contains a single character if it is printable, or ``None`` if it is not printable (like a function key which has no corresponding character).
+### Key Event
 
-To illustrate the difference between `key` and `char`, try `key01.py` with the space key. You should see something like the following:
+The key event contains the following attributes which your app can use to know how to respond.
 
-```{.textual path="docs/examples/guide/input/key01.py", press="space,_"}
+#### key
 
-```
+The `key` attribute is a string which identifies the key that was pressed. The value of `key` will be a single character for letters and numbers, or a longer identifier for other keys.
+
+Some keys may be combined with the ++shift++ key. In the case of letters, this will result in a capital letter as you might expect. For non-printable keys, the `key` attribute will be prefixed with `shift+`. For example, ++shift+home++ will produce an event with `key="shift+home"`.
+
+Many keys can also be combined with ++ctrl++ which will prefix the key with `ctrl+`. For instance, ++ctrl+p++ will produce an event with `key="ctrl+p"`.
+
+!!! warning
+
+    Not all keys combinations are supported in terminals and some keys may be intercepted by your OS. If in doubt, run `textual keys` from the command line.
+
+#### character
+
+If the key has an associated printable character, then `character` will contain a string with a single Unicode character. If there is no printable character for the key (such as for function keys) then `character` will be `None`.
+
+For example the ++p++ key will produce `character="p"` but ++f2++ will produce `character=None`.
+
+#### name
+
+The `name` attribute is similar to `key` but, unlike `key`, is guaranteed to be valid within a Python function name. Textual derives `name` from the `key` attribute by lower casing it and replacing `+` with `_`. Upper case letters are prefixed with `upper_` to distinguish them from lower case names.
+
+For example, ++ctrl+p++ produces `name="ctrl_p"` and ++shift+p++ produces `name="upper_p"`.
+
+#### is_printable
+
+The `is_printable` attribute is a boolean which indicates if the key would typically result in something that could be used in an input widget. If `is_printable` is `False` then the key is a control code or function key that you wouldn't expect to produce anything in an input.
+
+#### aliases
+
+Some keys or combinations of keys can produce the same event. For instance, the ++tab++ key is indistinguishable from ++ctrl+i++ in the terminal. For such keys, Textual events will contain a list of the possible keys that may have produced this event. In the case of ++tab++, the `aliases` attribute will contain `["tab", "ctrl+i"]`
 
-Note that the `key` attribute contains the word "space" while the `char` attribute contains a literal space.
 
 ### Key methods
 
-Textual offers a convenient way of handling specific keys. If you create a method beginning with `key_` followed by the name of a key, then that method will be called in response to the key.
+Textual offers a convenient way of handling specific keys. If you create a method beginning with `key_` followed by the key name (the event's `name` attribute), then that method will be called in response to the key press.
 
 Let's add a key method to the example code.
 
@@ -127,24 +154,28 @@ Note how the footer displays bindings and makes them clickable.
     Multiple keys can be bound to a single action by comma-separating them.
     For example, `("r,t", "add_bar('red')", "Add Red")` means both ++r++ and ++t++ are bound to `add_bar('red')`.
 
-
-!!! note
-
-    Ordinarily a binding on a focused widget has precedence over the same key binding at a higher level. However, bindings at the `App` or `Screen` level always have priority.
-
-    The priority of a single binding can be controlled with the `priority` parameter of a `Binding` instance. Set it to `True` to give it priority, or `False` to not.
-
-    The default priority of all bindings on a class can be controlled with the `PRIORITY_BINDINGS` class variable. Set it to `True` or `False` to set the default priroty for all `BINDINGS`.
-
 ### Binding class
 
 The tuple of three strings may be enough for simple bindings, but you can also replace the tuple with a [Binding][textual.binding.Binding] instance which exposes a few more options.
 
-### Why use bindings?
+### Priority bindings
 
-Bindings are particularly useful for configurable hot-keys. Bindings can also be inspected in widgets such as [Footer](../widgets/footer.md).
+Individual bindings may be marked as a *priority*, which means they will be checked prior to the bindings of the focused widget. This feature is often used to create hot-keys on the app or screen. Such bindings can not be disabled by binding the same key on a widget.
+
+You can create priority key bindings by setting `priority=True` on the Binding object. Textual uses this feature to add a default binding for ++ctrl+c++ so there is always a way to exit the app. Here's the bindings from the App base class. Note the first binding is set as a priority:
+
+```python
+    BINDINGS = [
+        Binding("ctrl+c", "quit", "Quit", show=False, priority=True),
+        Binding("tab", "focus_next", "Focus Next", show=False),
+        Binding("shift+tab", "focus_previous", "Focus Previous", show=False),
+    ]
+```
+
+### Show bindings
+
+The [footer](../widgets/footer.md) widget can inspect bindings to display available keys. If you don't want a binding to display in the footer you can set `show=False`. The default bindings on App do this so that the standard ++ctrl+c++, ++tab++ and ++shift+tab++ bindings don't typically appear in the footer.
 
-In a future version of Textual it will also be possible to specify bindings in a configuration file, which will allow users to override app bindings.
 
 ## Mouse Input
 

src/textual/app.py

@@ -232,8 +232,6 @@ class App(Generic[ReturnType], DOMNode):
     }
     """
 
-    PRIORITY_BINDINGS = True
-
     SCREENS: dict[str, Screen | Callable[[], Screen]] = {}
     _BASE_PATH: str | None = None
     CSS_PATH: CSSPathType = None
@@ -242,10 +240,8 @@ class App(Generic[ReturnType], DOMNode):
 
     BINDINGS = [
         Binding("ctrl+c", "quit", "Quit", show=False, priority=True),
-        Binding("tab", "focus_next", "Focus Next", show=False, priority=False),
+        Binding("tab", "focus_next", "Focus Next", show=False),
-        Binding(
+        Binding("shift+tab", "focus_previous", "Focus Previous", show=False),
-            "shift+tab", "focus_previous", "Focus Previous", show=False, priority=False
-        ),
     ]
 
     title: Reactive[str] = Reactive("")

src/textual/binding.py

@@ -5,6 +5,7 @@ from typing import Iterable, MutableMapping
 
 import rich.repr
 
+from textual.keys import _character_to_key
 from textual._typing import TypeAlias
 
 BindingType: TypeAlias = "Binding | tuple[str, str, str]"
@@ -18,6 +19,10 @@ class NoBinding(Exception):
     """A binding was not found."""
 
 
+class InvalidBinding(Exception):
+    """Binding key is in an invalid format."""
+
+
 @dataclass(frozen=True)
 class Binding:
     """The configuration of a key binding."""
@@ -32,8 +37,8 @@ class Binding:
     """bool: Show the action in Footer, or False to hide."""
     key_display: str | None = None
     """str | None: How the key should be shown in footer."""
-    priority: bool | None = None
+    priority: bool = False
-    """bool | None: Is this a priority binding, checked form app down to focused widget?"""
+    """bool: Enable priority binding for this key."""
 
 
 @rich.repr.auto
@@ -43,13 +48,11 @@ class Bindings:
     def __init__(
         self,
         bindings: Iterable[BindingType] | None = None,
-        default_priority: bool | None = None,
     ) -> None:
         """Initialise a collection of bindings.
 
         Args:
             bindings (Iterable[BindingType] | None, optional): An optional set of initial bindings.
-            default_priority (bool | None, optional): The default priority of the bindings.
 
         Note:
             The iterable of bindings can contain either a `Binding`
@@ -71,17 +74,20 @@ class Bindings:
                 # be a list of keys, so now we unroll that single Binding
                 # into a (potential) collection of Binding instances.
                 for key in binding.key.split(","):
+                    key = key.strip()
+                    if not key:
+                        raise InvalidBinding(
+                            f"Can not bind empty string in {binding.key!r}"
+                        )
+                    if len(key) == 1:
+                        key = _character_to_key(key)
                     yield Binding(
-                        key=key.strip(),
+                        key=key,
                         action=binding.action,
                         description=binding.description,
                         show=binding.show,
                         key_display=binding.key_display,
-                        priority=(
+                        priority=binding.priority,
-                            default_priority
-                            if binding.priority is None
-                            else binding.priority
-                        ),
                     )
 
         self.keys: MutableMapping[str, Binding] = (

src/textual/cli/cli.py

@@ -127,7 +127,7 @@ def colors():
 
 @run.command("keys")
 def keys():
-    """Show key events"""
+    """Show key events."""
     from textual.cli.previews import keys
 
     keys.app.run()

src/textual/cli/previews/keys.py

@@ -9,7 +9,7 @@ from textual.widgets import Button, Header, TextLog
 INSTRUCTIONS = """\
 Press some keys!    
 
-Because we want to display all the keys, Ctrl+C won't work for this example. Use the button below to quit.\
+Because we want to display all the keys, ctrl+C won't quit this example. Use the Quit button below to exit the app.\
 """
 
 

src/textual/dom.py

@@ -92,9 +92,6 @@ class DOMNode(MessagePump):
     # Virtual DOM nodes
     COMPONENT_CLASSES: ClassVar[set[str]] = set()
 
-    # Should the content of BINDINGS be treated as priority bindings?
-    PRIORITY_BINDINGS: ClassVar[bool] = False
-
     # Mapping of key bindings
     BINDINGS: ClassVar[list[BindingType]] = []
 
@@ -233,13 +230,13 @@ class DOMNode(MessagePump):
 
         for base in reversed(cls.__mro__):
             if issubclass(base, DOMNode):
-                # See if the current class wants to set the bindings as
-                # priority bindings. If it doesn't have that property on the
-                # class, go with what we saw last.
-                priority = base.__dict__.get("PRIORITY_BINDINGS", priority)
                 if not base._inherit_bindings:
                     bindings.clear()
-                bindings.append(Bindings(base.__dict__.get("BINDINGS", []), priority))
+                bindings.append(
+                    Bindings(
+                        base.__dict__.get("BINDINGS", []),
+                    )
+                )
         keys = {}
         for bindings_ in bindings:
             keys.update(bindings_.keys)

src/textual/events.py

@@ -16,7 +16,6 @@ if TYPE_CHECKING:
     from .timer import Timer as TimerClass
     from .timer import TimerCallback
     from .widget import Widget
-    import asyncio
 
 
 @rich.repr.auto
@@ -183,7 +182,7 @@ class MouseRelease(Event, bubble=False):
 
 
 class InputEvent(Event):
-    pass
+    """Base class for input events."""
 
 
 @rich.repr.auto
@@ -191,47 +190,56 @@ class Key(InputEvent):
     """Sent when the user hits a key on the keyboard.
 
     Args:
-        sender (MessageTarget): The sender of the event (the App).
+        sender (MessageTarget): The sender of the event (always the App).
-        key (str): A key name (textual.keys.Keys).
+        key (str): The key that was pressed.
-        char (str | None, optional): A printable character or None if it is not printable.
+        character (str | None, optional): A printable character or ``None`` if it is not printable.
 
     Attributes:
-        key_aliases (list[str]): The aliases for the key, including the key itself
+        aliases (list[str]): The aliases for the key, including the key itself.
     """
 
-    __slots__ = ["key", "char", "key_aliases"]
+    __slots__ = ["key", "character", "aliases"]
 
-    def __init__(self, sender: MessageTarget, key: str, char: str | None) -> None:
+    def __init__(self, sender: MessageTarget, key: str, character: str | None) -> None:
         super().__init__(sender)
         self.key = key
-        self.char = (key if len(key) == 1 else None) if char is None else char
+        self.character = (
-        self.key_aliases = [_normalize_key(alias) for alias in _get_key_aliases(key)]
+            (key if len(key) == 1 else None) if character is None else character
+        )
+        self.aliases = _get_key_aliases(key)
 
     def __rich_repr__(self) -> rich.repr.Result:
         yield "key", self.key
-        yield "char", self.char
+        yield "character", self.character
+        yield "name", self.name
         yield "is_printable", self.is_printable
-        yield "key_aliases", self.key_aliases, [self.key_name]
+        yield "aliases", self.aliases, [self.key]
 
     @property
-    def key_name(self) -> str | None:
+    def name(self) -> str:
         """Name of a key suitable for use as a Python identifier."""
-        return _normalize_key(self.key)
+        return _key_to_identifier(self.key).lower()
+
+    @property
+    def name_aliases(self) -> list[str]:
+        """The corresponding name for every alias in `aliases` list."""
+        return [_key_to_identifier(key) for key in self.aliases]
 
     @property
     def is_printable(self) -> bool:
-        """Return True if the key is printable. Currently, we assume any key event that
+        """Check if the key is printable (produces a unicode character).
-        isn't defined in key bindings is printable.
 
         Returns:
             bool: True if the key is printable.
         """
-        return False if self.char is None else self.char.isprintable()
+        return False if self.character is None else self.character.isprintable()
 
 
-def _normalize_key(key: str) -> str:
+def _key_to_identifier(key: str) -> str:
     """Convert the key string to a name suitable for use as a Python identifier."""
-    return key.replace("+", "_")
+    if len(key) == 1 and key.isupper():
+        key = f"upper_{key.lower()}"
+    return key.replace("+", "_").lower()
 
 
 @rich.repr.auto

src/textual/keys.py

@@ -70,10 +70,10 @@ class Keys(str, Enum):
     ControlShift9 = "ctrl+shift+9"
     ControlShift0 = "ctrl+shift+0"
 
-    ControlBackslash = "ctrl+\\"
+    ControlBackslash = "ctrl+backslash"
-    ControlSquareClose = "ctrl+]"
+    ControlSquareClose = "ctrl+right_square_bracked"
-    ControlCircumflex = "ctrl+^"
+    ControlCircumflex = "ctrl+circumflex_accent"
-    ControlUnderscore = "ctrl+_"
+    ControlUnderscore = "ctrl+underscore"
 
     Left = "left"
     Right = "right"
@@ -256,3 +256,14 @@ def _get_key_display(key: str) -> str:
     if unicode_character.isprintable():
         return unicode_character
     return upper_original
+
+
+def _character_to_key(character: str) -> str:
+    """Convert a single character to a key value."""
+    assert len(character) == 1
+    if not character.isalnum():
+        key = unicodedata.name(character).lower().replace("-", "_").replace(" ", "_")
+    else:
+        key = character
+    key = KEY_NAME_REPLACEMENTS.get(key, key)
+    return key

src/textual/message.py

@@ -24,7 +24,6 @@ class Message:
 
     __slots__ = [
         "sender",
-        "name",
         "time",
         "_forwarded",
         "_no_default_action",
@@ -40,13 +39,14 @@ class Message:
 
     def __init__(self, sender: MessageTarget) -> None:
         self.sender = sender
-        self.name = camel_to_snake(self.__class__.__name__)
+
         self.time = _clock.get_time_no_wait()
         self._forwarded = False
         self._no_default_action = False
         self._stop_propagation = False
+        name = camel_to_snake(self.__class__.__name__)
         self._handler_name = (
-            f"on_{self.namespace}_{self.name}" if self.namespace else f"on_{self.name}"
+            f"on_{self.namespace}_{name}" if self.namespace else f"on_{name}"
         )
         super().__init__()
 

src/textual/message_pump.py

@@ -593,12 +593,12 @@ class MessagePump(metaclass=MessagePumpMeta):
 
         handled = False
         invoked_method = None
-        key_name = event.key_name
+        key_name = event.name
         if not key_name:
             return False
 
-        for key_alias in event.key_aliases:
+        for key_method_name in event.name_aliases:
-            key_method = get_key_handler(self, key_alias)
+            key_method = get_key_handler(self, key_method_name)
             if key_method is not None:
                 if invoked_method:
                     _raise_duplicate_key_handlers_error(

src/textual/screen.py

@@ -29,7 +29,6 @@ class Screen(Widget):
     # The screen is a special case and unless a class that inherits from us
     # says otherwise, all screen-level bindings should be treated as having
     # priority.
-    PRIORITY_BINDINGS = True
 
     DEFAULT_CSS = """
     Screen {

src/textual/widgets/_input.py

@@ -233,8 +233,8 @@ class Input(Widget, can_focus=True):
             return
         elif event.is_printable:
             event.stop()
-            assert event.char is not None
+            assert event.character is not None
-            self.insert_text_at_cursor(event.char)
+            self.insert_text_at_cursor(event.character)
             event.prevent_default()
 
     def on_paste(self, event: events.Paste) -> None:

src/textual/widgets/_text_log.py

@@ -66,13 +66,15 @@ class TextLog(ScrollView, can_focus=True):
         content: RenderableType | object,
         width: int | None = None,
         expand: bool = False,
+        shrink: bool = True,
     ) -> None:
         """Write text or a rich renderable.
 
         Args:
             content (RenderableType): Rich renderable (or text).
-            width (int): Width to render or None to use optimal width. Defaults to None.
+            width (int): Width to render or None to use optimal width. Defaults to `None`.
-            expand (bool): Enable expand to widget width, or False to use `width`.
+            expand (bool): Enable expand to widget width, or False to use `width`. Defaults to `False`.
+            shrink (bool): Enable shrinking of content to fit width. Defaults to `True`.
         """
 
         renderable: RenderableType
@@ -95,14 +97,17 @@ class TextLog(ScrollView, can_focus=True):
         if isinstance(renderable, Text) and not self.wrap:
             render_options = render_options.update(overflow="ignore", no_wrap=True)
 
-        if expand:
+        render_width = measure_renderables(
-            render_width = self.scrollable_content_region.width
+            console, render_options, [renderable]
-        else:
+        ).maximum
-            render_width = (
+        container_width = (
-                measure_renderables(console, render_options, [renderable]).maximum
+            self.scrollable_content_region.width if width is None else width
-                if width is None
+        )
-                else width
+
-            )
+        if expand and render_width < container_width:
+            render_width = container_width
+        if shrink and render_width > container_width:
+            render_width = container_width
 
         segments = self.app.console.render(
             renderable, render_options.update_width(render_width)

tests/snapshot_tests/conftest.py

@@ -191,10 +191,9 @@ def pytest_terminal_summary(
     console = Console(legacy_windows=False, force_terminal=True)
     if diffs:
         snapshot_report_location = config._textual_snapshot_html_report
-        console.rule("[b red]Textual Snapshot Report", style="red")
+        console.print("[b red]Textual Snapshot Report", style="red")
         console.print(
             f"\n[black on red]{len(diffs)} mismatched snapshots[/]\n"
             f"\n[b]View the [link=file://{snapshot_report_location}]failure report[/].\n"
         )
         console.print(f"[dim]{snapshot_report_location}\n")
-        console.rule(style="red")

tests/test_binding.py

@@ -2,7 +2,8 @@ from string import ascii_lowercase
 
 import pytest
 
-from textual.binding import Bindings, Binding, BindingError, NoBinding
+from textual.app import App
+from textual.binding import Bindings, Binding, BindingError, NoBinding, InvalidBinding
 
 BINDING1 = Binding("a,b", action="action1", description="description1")
 BINDING2 = Binding("c", action="action2", description="description2")
@@ -13,45 +14,78 @@ BINDING3 = Binding(" d   , e ", action="action3", description="description3")
 def bindings():
     yield Bindings([BINDING1, BINDING2])
 
+
 @pytest.fixture
 def more_bindings():
     yield Bindings([BINDING1, BINDING2, BINDING3])
 
+
 def test_bindings_get_key(bindings):
-    assert bindings.get_key("b") == Binding("b", action="action1", description="description1")
+    assert bindings.get_key("b") == Binding(
+        "b", action="action1", description="description1"
+    )
     assert bindings.get_key("c") == BINDING2
     with pytest.raises(NoBinding):
         bindings.get_key("control+meta+alt+shift+super+hyper+t")
 
+
 def test_bindings_get_key_spaced_list(more_bindings):
     assert more_bindings.get_key("d").action == more_bindings.get_key("e").action
 
+
 def test_bindings_merge_simple(bindings):
     left = Bindings([BINDING1])
     right = Bindings([BINDING2])
     assert Bindings.merge([left, right]).keys == bindings.keys
 
+
 def test_bindings_merge_overlap():
     left = Bindings([BINDING1])
-    another_binding = Binding("a", action="another_action", description="another_description")
+    another_binding = Binding(
+        "a", action="another_action", description="another_description"
+    )
     assert Bindings.merge([left, Bindings([another_binding])]).keys == {
         "a": another_binding,
         "b": Binding("b", action="action1", description="description1"),
     }
 
+
 def test_bad_binding_tuple():
     with pytest.raises(BindingError):
         _ = Bindings((("a", "action"),))
     with pytest.raises(BindingError):
-        _ = Bindings((("a", "action", "description","too much"),))
+        _ = Bindings((("a", "action", "description", "too much"),))
+
 
 def test_binding_from_tuples():
-    assert Bindings((( BINDING2.key, BINDING2.action, BINDING2.description),)).get_key("c") == BINDING2
+    assert (
+        Bindings(((BINDING2.key, BINDING2.action, BINDING2.description),)).get_key("c")
+        == BINDING2
+    )
+
 
 def test_shown():
-    bindings = Bindings([
+    bindings = Bindings(
-        Binding(
+        [
-            key, action=f"action_{key}", description=f"Emits {key}",show=bool(ord(key)%2)
+            Binding(
-        ) for key in ascii_lowercase
+                key,
-    ])
+                action=f"action_{key}",
-    assert len(bindings.shown_keys)==(len(ascii_lowercase)/2)
+                description=f"Emits {key}",
+                show=bool(ord(key) % 2),
+            )
+            for key in ascii_lowercase
+        ]
+    )
+    assert len(bindings.shown_keys) == (len(ascii_lowercase) / 2)
+
+
+def test_invalid_binding():
+    with pytest.raises(InvalidBinding):
+
+        class BrokenApp(App):
+            BINDINGS = [(",,,", "foo", "Broken")]
+
+    with pytest.raises(InvalidBinding):
+
+        class BrokenApp(App):
+            BINDINGS = [(", ,", "foo", "Broken")]

tests/test_binding_inheritance.py

@@ -57,7 +57,7 @@ async def test_just_app_no_bindings() -> None:
 class AlphaBinding(App[None]):
     """An app with a simple alpha key binding."""
 
-    BINDINGS = [Binding("a", "a", "a")]
+    BINDINGS = [Binding("a", "a", "a", priority=True)]
 
 
 async def test_just_app_alpha_binding() -> None:
@@ -81,8 +81,7 @@ async def test_just_app_alpha_binding() -> None:
 class LowAlphaBinding(App[None]):
     """An app with a simple low-priority alpha key binding."""
 
-    PRIORITY_BINDINGS = False
+    BINDINGS = [Binding("a", "a", "a", priority=False)]
-    BINDINGS = [Binding("a", "a", "a")]
 
 
 async def test_just_app_low_priority_alpha_binding() -> None:
@@ -106,7 +105,7 @@ async def test_just_app_low_priority_alpha_binding() -> None:
 class ScreenWithBindings(Screen):
     """A screen with a simple alpha key binding."""
 
-    BINDINGS = [Binding("a", "a", "a")]
+    BINDINGS = [Binding("a", "a", "a", priority=True)]
 
 
 class AppWithScreenThatHasABinding(App[None]):
@@ -144,8 +143,7 @@ async def test_app_screen_with_bindings() -> None:
 class ScreenWithLowBindings(Screen):
     """A screen with a simple low-priority alpha key binding."""
 
-    PRIORITY_BINDINGS = False
+    BINDINGS = [Binding("a", "a", "a", priority=False)]
-    BINDINGS = [Binding("a", "a", "a")]
 
 
 class AppWithScreenThatHasALowBinding(App[None]):

tests/test_keys.py

@@ -0,0 +1,50 @@
+import pytest
+
+from textual.app import App
+from textual.keys import _character_to_key
+
+
+@pytest.mark.parametrize(
+    "character,key",
+    [
+        ("1", "1"),
+        ("2", "2"),
+        ("a", "a"),
+        ("z", "z"),
+        ("_", "underscore"),
+        (" ", "space"),
+        ("~", "tilde"),
+        ("?", "question_mark"),
+        ("£", "pound_sign"),
+        (",", "comma"),
+    ],
+)
+def test_character_to_key(character: str, key: str) -> None:
+    assert _character_to_key(character) == key
+
+
+async def test_character_bindings():
+    """Test you can bind to a character as well as a longer key name."""
+    counter = 0
+
+    class BindApp(App):
+        BINDINGS = [(".,~,space", "increment", "foo")]
+
+        def action_increment(self) -> None:
+            nonlocal counter
+            counter += 1
+
+    app = BindApp()
+    async with app.run_test() as pilot:
+        await pilot.press(".")
+        await pilot.pause()
+        assert counter == 1
+        await pilot.press("~")
+        await pilot.pause()
+        assert counter == 2
+        await pilot.press(" ")
+        await pilot.pause()
+        assert counter == 3
+        await pilot.press("x")
+        await pilot.pause()
+        assert counter == 3

tests/test_message_pump.py

@@ -17,7 +17,7 @@ class ValidWidget(Widget):
 
 async def test_dispatch_key_valid_key():
     widget = ValidWidget()
-    result = await widget.dispatch_key(Key(widget, key="x", char="x"))
+    result = await widget.dispatch_key(Key(widget, key="x", character="x"))
     assert result is True
     assert widget.called_by == widget.key_x
 
@@ -26,7 +26,7 @@ async def test_dispatch_key_valid_key_alias():
     """When you press tab or ctrl+i, it comes through as a tab key event, but handlers for
     tab and ctrl+i are both considered valid."""
     widget = ValidWidget()
-    result = await widget.dispatch_key(Key(widget, key="tab", char="\t"))
+    result = await widget.dispatch_key(Key(widget, key="tab", character="\t"))
     assert result is True
     assert widget.called_by == widget.key_ctrl_i
 
@@ -52,5 +52,5 @@ async def test_dispatch_key_raises_when_conflicting_handler_aliases():
     In the terminal, they're the same thing, so we fail fast via exception here."""
     widget = DuplicateHandlersWidget()
     with pytest.raises(DuplicateKeyHandlers):
-        await widget.dispatch_key(Key(widget, key="tab", char="\t"))
+        await widget.dispatch_key(Key(widget, key="tab", character="\t"))
     assert widget.called_by == widget.key_tab

tests/test_xterm_parser.py

@@ -106,7 +106,7 @@ def test_cant_match_escape_sequence_too_long(parser):
     # The rest of the characters correspond to the expected key presses
     events = events[1:]
     for index, character in enumerate(sequence[1:]):
-        assert events[index].char == character
+        assert events[index].character == character
 
 
 @pytest.mark.parametrize(