calculator example

CHANGELOG.md

@@ -5,7 +5,11 @@ 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/).
 
-## [Unreleased] - yyyy-mm-dd
+## [0.1.7] - 2021-07-14
 
-Here we write upgrading notes for brands. It's a team effort to make them as
+### Changed
-straightforward as possible.
+
+- Added functionality to calculator example.
+- Scrollview now shows scrollbars automatically
+- New handler system for messages that doesn't require inheritance
+- Improved traceback handling

examples/calculator.py

@@ -1,17 +1,27 @@
+from decimal import Decimal
+
 from rich.align import Align
-from rich.console import Console, ConsoleOptions, RenderResult
+from rich.console import Console, ConsoleOptions, RenderResult, RenderableType
+from rich.padding import Padding
 from rich.text import Text
 
+
 from textual.app import App
 from textual import events
+from textual.message import Message
+from textual.reactive import Reactive
 from textual.view import View
-from textual.widgets import Button, Static
+from textual.widget import Widget
+from textual.widgets import Button
 from textual.layouts.grid import GridLayout
 
 try:
     from pyfiglet import Figlet
 except ImportError:
     print("Please install pyfiglet to run this example")
+    import sys
+
+    sys.exit()
 
 
 class FigletText:
@@ -24,10 +34,8 @@ class FigletText:
         self, console: Console, options: ConsoleOptions
     ) -> RenderResult:
         size = min(options.max_width / 2, options.max_height)
-
-        text = self.text
         if size < 4:
-            yield Text(text, style="bold")
+            yield Text(self.text, style="bold")
         else:
             if size < 7:
                 font_name = "mini"
@@ -37,42 +45,148 @@ class FigletText:
                 font_name = "standard"
             else:
                 font_name = "big"
-            font = Figlet(font=font_name)
+            font = Figlet(font=font_name, width=options.max_width)
-            yield Text(font.renderText(text).rstrip("\n"), style="bold")
+            yield Text(font.renderText(self.text).rstrip("\n"), style="bold")
+
+
+class Numbers(Widget):
+    """The digital display of the calculator."""
+
+    value: Reactive[str] = Reactive("0")
+
+    def render(self) -> RenderableType:
+        return Padding(
+            Align.right(FigletText(self.value), vertical="middle"),
+            (0, 1),
+            style="white on rgb(51,51,51)",
+        )
 
 
 class CalculatorApp(App):
-    async def on_startup(self, event: events.Startup) -> None:
+    """A working calculator app."""
 
+    async def on_load(self, event: events.Load) -> None:
+        """Sent when the app starts, but before displaying anything."""
+
+        self.left = Decimal("0")
+        self.right = Decimal("0")
+        self.value = ""
+        self.operator = "+"
+        self.numbers = Numbers()
+
+        def make_button(text: str, style: str) -> Button:
+            """Create a button with the given Figlet label."""
+            return Button(FigletText(text), style=style, name=text)
+
+        dark = "white on rgb(51,51,51)"
+        light = "black on rgb(165,165,165)"
+        yellow = "white on rgb(255,159,7)"
+
+        button_styles = {
+            "AC": light,
+            "C": light,
+            "+/-": light,
+            "%": light,
+            "/": yellow,
+            "X": yellow,
+            "-": yellow,
+            "+": yellow,
+            "=": yellow,
+        }
+
+        # Make all the buttons
+        self.buttons = {
+            name: make_button(name, button_styles.get(name, dark))
+            for name in "+/-,%,/,7,8,9,X,4,5,6,-,1,2,3,+,.,=".split(",")
+        }
+
+        self.zero = make_button("0", dark)
+        self.ac = make_button("AC", light)
+        self.c = make_button("C", light)
+        self.c.visible = False
+
+    async def on_startup(self, event: events.Startup) -> None:
+        """Sent when the app has gone full screen."""
+
+        # Create the layout which defines where our widgets will go
         layout = GridLayout(gap=(2, 1), gutter=1, align=("center", "center"))
         await self.push_view(View(layout=layout))
 
+        # Create rows / columns / areas
         layout.add_column("col", max_size=30, repeat=4)
-        layout.add_row("numbers")
+        layout.add_row("numbers", max_size=15)
         layout.add_row("row", max_size=15, repeat=5)
         layout.add_areas(
-            numbers="col1-start|col4-end,numbers", zero="col1-start|col2-end,row5"
+            clear="col1,row1",
+            numbers="col1-start|col4-end,numbers",
+            zero="col1-start|col2-end,row5",
         )
-
+        # Place out widgets in to the layout
-        def make_button(text: str) -> Button:
+        layout.place(clear=self.c)
-            return Button(FigletText(text), style="white on rgb(51,51,51)")
-
-        buttons = {
-            name: make_button(name)
-            for name in "AC,+/-,%,/,7,8,9,X,4,5,6,-,1,2,3,+,.,=".split(",")
-        }
-        for name in ("AC", "+/-", "%"):
-            buttons[name].style = "black on rgb(165,165,165)"
-        for name in "/X-+=":
-            buttons[name].style = "white on rgb(255,159,7)"
-
-        numbers = Align.right(FigletText("0"), vertical="middle")
-
         layout.place(
-            *buttons.values(),
+            *self.buttons.values(), clear=self.ac, numbers=self.numbers, zero=self.zero
-            numbers=Static(numbers, padding=(0, 1), style="white on rgb(51,51,51)"),
-            zero=make_button("0"),
         )
 
+    async def message_button_pressed(self, message: Message) -> None:
+        """A message sent by the button widget"""
+
+        assert isinstance(message.sender, Button)
+        button_name = message.sender.name
+
+        def do_math() -> bool:
+            operator = self.operator
+            right = self.right
+            if operator == "+":
+                self.left += right
+            elif operator == "-":
+                self.left -= right
+            elif operator == "/":
+                try:
+                    self.left /= right
+                except ZeroDivisionError:
+                    self.numbers.value = "Error"
+                    return False
+            elif operator == "X":
+                self.left *= right
+            return True
+
+        if button_name.isdigit():
+            self.value = self.value.lstrip("0") + button_name
+            self.numbers.value = self.value
+        elif button_name == "+/-":
+            self.value = str(Decimal(self.value or "0") * -1)
+            self.numbers.value = self.value
+        elif button_name == "%":
+            self.value = str(Decimal(self.value or "0") / Decimal(100))
+            self.numbers.value = self.value
+        elif button_name == ".":
+            if "." not in self.value:
+                self.value += "."
+                self.numbers.value = self.value
+        elif button_name == "AC":
+            self.value = ""
+            self.left = self.right = Decimal(0)
+            self.operator = "+"
+            self.numbers.value = "0"
+        elif button_name == "C":
+            self.value = ""
+            self.numbers.value = "0"
+        elif button_name in ("+", "-", "/", "X"):
+            self.right = Decimal(self.value or "0")
+            if do_math():
+                self.numbers.value = str(self.left)
+            self.value = ""
+            self.operator = button_name
+        elif button_name == "=":
+            if self.value:
+                self.right = Decimal(self.value or "0")
+            if do_math():
+                self.numbers.value = str(self.left)
+            self.value = ""
+
+        show_ac = self.value in ("", "0") and self.numbers.value == "0"
+        self.c.visible = not show_ac
+        self.ac.visible = show_ac
+
 
 CalculatorApp.run(title="Calculator Test")

poetry.lock

@@ -6,6 +6,17 @@ category = "dev"
 optional = false
 python-versions = "*"
 
+[[package]]
+name = "astunparse"
+version = "1.6.3"
+description = "An AST unparser for Python"
+category = "dev"
+optional = false
+python-versions = "*"
+
+[package.dependencies]
+six = ">=1.6.1,<2.0"
+
 [[package]]
 name = "atomicwrites"
 version = "1.4.0"
@@ -50,6 +61,14 @@ typing-extensions = ">=3.7.4"
 colorama = ["colorama (>=0.4.3)"]
 d = ["aiohttp (>=3.3.2)", "aiohttp-cors"]
 
+[[package]]
+name = "cached-property"
+version = "1.5.2"
+description = "A decorator for caching properties in classes."
+category = "dev"
+optional = false
+python-versions = "*"
+
 [[package]]
 name = "click"
 version = "8.0.1"
@@ -92,6 +111,20 @@ python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, <4"
 [package.extras]
 toml = ["toml"]
 
+[[package]]
+name = "ghp-import"
+version = "2.0.1"
+description = "Copy your docs directly to the gh-pages branch."
+category = "dev"
+optional = false
+python-versions = "*"
+
+[package.dependencies]
+python-dateutil = ">=2.8.1"
+
+[package.extras]
+dev = ["twine", "markdown", "flake8"]
+
 [[package]]
 name = "importlib-metadata"
 version = "4.6.1"
@@ -117,6 +150,128 @@ category = "dev"
 optional = false
 python-versions = "*"
 
+[[package]]
+name = "jinja2"
+version = "3.0.1"
+description = "A very fast and expressive template engine."
+category = "dev"
+optional = false
+python-versions = ">=3.6"
+
+[package.dependencies]
+MarkupSafe = ">=2.0"
+
+[package.extras]
+i18n = ["Babel (>=2.7)"]
+
+[[package]]
+name = "markdown"
+version = "3.3.4"
+description = "Python implementation of Markdown."
+category = "dev"
+optional = false
+python-versions = ">=3.6"
+
+[package.dependencies]
+importlib-metadata = {version = "*", markers = "python_version < \"3.8\""}
+
+[package.extras]
+testing = ["coverage", "pyyaml"]
+
+[[package]]
+name = "markupsafe"
+version = "2.0.1"
+description = "Safely add untrusted strings to HTML/XML markup."
+category = "dev"
+optional = false
+python-versions = ">=3.6"
+
+[[package]]
+name = "mergedeep"
+version = "1.3.4"
+description = "A deep merge function for 🐍."
+category = "dev"
+optional = false
+python-versions = ">=3.6"
+
+[[package]]
+name = "mkdocs"
+version = "1.2.1"
+description = "Project documentation with Markdown."
+category = "dev"
+optional = false
+python-versions = ">=3.6"
+
+[package.dependencies]
+click = ">=3.3"
+ghp-import = ">=1.0"
+importlib-metadata = ">=3.10"
+Jinja2 = ">=2.10.1"
+Markdown = ">=3.2.1"
+mergedeep = ">=1.3.4"
+packaging = ">=20.5"
+PyYAML = ">=3.10"
+pyyaml-env-tag = ">=0.1"
+watchdog = ">=2.0"
+
+[package.extras]
+i18n = ["babel (>=2.9.0)"]
+
+[[package]]
+name = "mkdocs-autorefs"
+version = "0.2.1"
+description = "Automatically link across pages in MkDocs."
+category = "dev"
+optional = false
+python-versions = ">=3.6,<4.0"
+
+[package.dependencies]
+Markdown = ">=3.3,<4.0"
+mkdocs = ">=1.1,<2.0"
+
+[[package]]
+name = "mkdocs-material"
+version = "7.1.10"
+description = "A Material Design theme for MkDocs"
+category = "dev"
+optional = false
+python-versions = "*"
+
+[package.dependencies]
+markdown = ">=3.2"
+mkdocs = ">=1.1"
+mkdocs-material-extensions = ">=1.0"
+Pygments = ">=2.4"
+pymdown-extensions = ">=7.0"
+
+[[package]]
+name = "mkdocs-material-extensions"
+version = "1.0.1"
+description = "Extension pack for Python Markdown."
+category = "dev"
+optional = false
+python-versions = ">=3.5"
+
+[package.dependencies]
+mkdocs-material = ">=5.0.0"
+
+[[package]]
+name = "mkdocstrings"
+version = "0.15.2"
+description = "Automatic documentation from sources, for MkDocs."
+category = "dev"
+optional = false
+python-versions = ">=3.6,<4.0"
+
+[package.dependencies]
+Jinja2 = ">=2.11.1,<4.0"
+Markdown = ">=3.3,<4.0"
+MarkupSafe = ">=1.1,<3.0"
+mkdocs = ">=1.1.1,<2.0.0"
+mkdocs-autorefs = ">=0.1,<0.3"
+pymdown-extensions = ">=6.3,<9.0"
+pytkdocs = ">=0.2.0,<0.12.0"
+
 [[package]]
 name = "mypy"
 version = "0.910"
@@ -192,6 +347,17 @@ category = "main"
 optional = false
 python-versions = ">=3.5"
 
+[[package]]
+name = "pymdown-extensions"
+version = "8.2"
+description = "Extension pack for Python Markdown."
+category = "dev"
+optional = false
+python-versions = ">=3.6"
+
+[package.dependencies]
+Markdown = ">=3.2"
+
 [[package]]
 name = "pyparsing"
 version = "2.4.7"
@@ -238,6 +404,52 @@ toml = "*"
 [package.extras]
 testing = ["fields", "hunter", "process-tests", "six", "pytest-xdist", "virtualenv"]
 
+[[package]]
+name = "python-dateutil"
+version = "2.8.2"
+description = "Extensions to the standard Python datetime module"
+category = "dev"
+optional = false
+python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,>=2.7"
+
+[package.dependencies]
+six = ">=1.5"
+
+[[package]]
+name = "pytkdocs"
+version = "0.11.1"
+description = "Load Python objects documentation."
+category = "dev"
+optional = false
+python-versions = ">=3.6.1,<4.0.0"
+
+[package.dependencies]
+astunparse = {version = ">=1.6.3,<2.0.0", markers = "python_version < \"3.9\""}
+cached-property = {version = ">=1.5.2,<2.0.0", markers = "python_version < \"3.8\""}
+typing-extensions = {version = ">=3.7.4.3,<4.0.0.0", markers = "python_version < \"3.8\""}
+
+[package.extras]
+numpy-style = ["docstring_parser (>=0.7.3,<0.8.0)"]
+
+[[package]]
+name = "pyyaml"
+version = "5.4.1"
+description = "YAML parser and emitter for Python"
+category = "dev"
+optional = false
+python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, !=3.5.*"
+
+[[package]]
+name = "pyyaml-env-tag"
+version = "0.1"
+description = "A custom YAML tag for referencing environment variables in YAML files. "
+category = "dev"
+optional = false
+python-versions = ">=3.6"
+
+[package.dependencies]
+pyyaml = "*"
+
 [[package]]
 name = "regex"
 version = "2021.7.6"
@@ -263,6 +475,14 @@ typing-extensions = {version = ">=3.7.4,<4.0.0", markers = "python_version < \"3
 [package.extras]
 jupyter = ["ipywidgets (>=7.5.1,<8.0.0)"]
 
+[[package]]
+name = "six"
+version = "1.16.0"
+description = "Python 2 and 3 compatibility utilities"
+category = "dev"
+optional = false
+python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*"
+
 [[package]]
 name = "toml"
 version = "0.10.2"
@@ -287,6 +507,17 @@ category = "main"
 optional = false
 python-versions = "*"
 
+[[package]]
+name = "watchdog"
+version = "2.1.3"
+description = "Filesystem events monitoring"
+category = "dev"
+optional = false
+python-versions = ">=3.6"
+
+[package.extras]
+watchmedo = ["PyYAML (>=3.10)", "argh (>=0.24.1)"]
+
 [[package]]
 name = "zipp"
 version = "3.5.0"
@@ -302,13 +533,17 @@ testing = ["pytest (>=4.6)", "pytest-checkdocs (>=2.4)", "pytest-flake8", "pytes
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.7"
-content-hash = "137e746aef38f8e8eac2674219503221c2705c80b9ee4b463129b1c47e459460"
+content-hash = "ac64f9d88e11df57c6fabe30fb9f39aee4ea9925809a8c850a61e0b4e92bf64f"
 
 [metadata.files]
 appdirs = [
     {file = "appdirs-1.4.4-py2.py3-none-any.whl", hash = "sha256:a841dacd6b99318a741b166adb07e19ee71a274450e68237b4650ca1055ab128"},
     {file = "appdirs-1.4.4.tar.gz", hash = "sha256:7d5d0167b2b1ba821647616af46a749d1c653740dd0d2415100fe26e27afdf41"},
 ]
+astunparse = [
+    {file = "astunparse-1.6.3-py2.py3-none-any.whl", hash = "sha256:c2652417f2c8b5bb325c885ae329bdf3f86424075c4fd1a128674bc6fba4b8e8"},
+    {file = "astunparse-1.6.3.tar.gz", hash = "sha256:5ad93a8456f0d084c3456d059fd9a92cce667963232cbf763eac3bc5b7940872"},
+]
 atomicwrites = [
     {file = "atomicwrites-1.4.0-py2.py3-none-any.whl", hash = "sha256:6d1784dea7c0c8d4a5172b6c620f40b6e4cbfdf96d783691f2e1302a7b88e197"},
     {file = "atomicwrites-1.4.0.tar.gz", hash = "sha256:ae70396ad1a434f9c7046fd2dd196fc04b12f9e91ffb859164193be8b6168a7a"},
@@ -320,6 +555,10 @@ attrs = [
 black = [
     {file = "black-20.8b1.tar.gz", hash = "sha256:1c02557aa099101b9d21496f8a914e9ed2222ef70336404eeeac8edba836fbea"},
 ]
+cached-property = [
+    {file = "cached-property-1.5.2.tar.gz", hash = "sha256:9fa5755838eecbb2d234c3aa390bd80fbd3ac6b6869109bfc1b499f7bd89a130"},
+    {file = "cached_property-1.5.2-py2.py3-none-any.whl", hash = "sha256:df4f613cf7ad9a588cc381aaf4a512d26265ecebd5eb9e1ba12f1319eb85a6a0"},
+]
 click = [
     {file = "click-8.0.1-py3-none-any.whl", hash = "sha256:fba402a4a47334742d782209a7c79bc448911afe1149d07bdabdf480b3e2f4b6"},
     {file = "click-8.0.1.tar.gz", hash = "sha256:8c04c11192119b1ef78ea049e0a6f0463e4c48ef00a30160c704337586f3ad7a"},
@@ -386,6 +625,9 @@ coverage = [
     {file = "coverage-5.5-pp37-none-any.whl", hash = "sha256:2a3859cb82dcbda1cfd3e6f71c27081d18aa251d20a17d87d26d4cd216fb0af4"},
     {file = "coverage-5.5.tar.gz", hash = "sha256:ebe78fe9a0e874362175b02371bdfbee64d8edc42a044253ddf4ee7d3c15212c"},
 ]
+ghp-import = [
+    {file = "ghp-import-2.0.1.tar.gz", hash = "sha256:753de2eace6e0f7d4edfb3cce5e3c3b98cd52aadb80163303d1d036bda7b4483"},
+]
 importlib-metadata = [
     {file = "importlib_metadata-4.6.1-py3-none-any.whl", hash = "sha256:9f55f560e116f8643ecf2922d9cd3e1c7e8d52e683178fecd9d08f6aa357e11e"},
     {file = "importlib_metadata-4.6.1.tar.gz", hash = "sha256:079ada16b7fc30dfbb5d13399a5113110dab1aa7c2bc62f66af75f0b717c8cac"},
@@ -394,6 +636,74 @@ iniconfig = [
     {file = "iniconfig-1.1.1-py2.py3-none-any.whl", hash = "sha256:011e24c64b7f47f6ebd835bb12a743f2fbe9a26d4cecaa7f53bc4f35ee9da8b3"},
     {file = "iniconfig-1.1.1.tar.gz", hash = "sha256:bc3af051d7d14b2ee5ef9969666def0cd1a000e121eaea580d4a313df4b37f32"},
 ]
+jinja2 = [
+    {file = "Jinja2-3.0.1-py3-none-any.whl", hash = "sha256:1f06f2da51e7b56b8f238affdd6b4e2c61e39598a378cc49345bc1bd42a978a4"},
+    {file = "Jinja2-3.0.1.tar.gz", hash = "sha256:703f484b47a6af502e743c9122595cc812b0271f661722403114f71a79d0f5a4"},
+]
+markdown = [
+    {file = "Markdown-3.3.4-py3-none-any.whl", hash = "sha256:96c3ba1261de2f7547b46a00ea8463832c921d3f9d6aba3f255a6f71386db20c"},
+    {file = "Markdown-3.3.4.tar.gz", hash = "sha256:31b5b491868dcc87d6c24b7e3d19a0d730d59d3e46f4eea6430a321bed387a49"},
+]
+markupsafe = [
+    {file = "MarkupSafe-2.0.1-cp36-cp36m-macosx_10_9_x86_64.whl", hash = "sha256:f9081981fe268bd86831e5c75f7de206ef275defcb82bc70740ae6dc507aee51"},
+    {file = "MarkupSafe-2.0.1-cp36-cp36m-manylinux1_i686.whl", hash = "sha256:0955295dd5eec6cb6cc2fe1698f4c6d84af2e92de33fbcac4111913cd100a6ff"},
+    {file = "MarkupSafe-2.0.1-cp36-cp36m-manylinux1_x86_64.whl", hash = "sha256:0446679737af14f45767963a1a9ef7620189912317d095f2d9ffa183a4d25d2b"},
+    {file = "MarkupSafe-2.0.1-cp36-cp36m-manylinux2010_i686.whl", hash = "sha256:f826e31d18b516f653fe296d967d700fddad5901ae07c622bb3705955e1faa94"},
+    {file = "MarkupSafe-2.0.1-cp36-cp36m-manylinux2010_x86_64.whl", hash = "sha256:fa130dd50c57d53368c9d59395cb5526eda596d3ffe36666cd81a44d56e48872"},
+    {file = "MarkupSafe-2.0.1-cp36-cp36m-manylinux2014_aarch64.whl", hash = "sha256:905fec760bd2fa1388bb5b489ee8ee5f7291d692638ea5f67982d968366bef9f"},
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+    {file = "watchdog-2.1.3-cp39-cp39-macosx_10_9_universal2.whl", hash = "sha256:d9456f0433845e7153b102fffeb767bde2406b76042f2216838af3b21707894e"},
+    {file = "watchdog-2.1.3-cp39-cp39-macosx_10_9_x86_64.whl", hash = "sha256:fd8c595d5a93abd441ee7c5bb3ff0d7170e79031520d113d6f401d0cf49d7c8f"},
+    {file = "watchdog-2.1.3-cp39-cp39-macosx_11_0_arm64.whl", hash = "sha256:0bcfe904c7d404eb6905f7106c54873503b442e8e918cc226e1828f498bdc0ca"},
+    {file = "watchdog-2.1.3-pp36-pypy36_pp73-macosx_10_9_x86_64.whl", hash = "sha256:bf84bd94cbaad8f6b9cbaeef43080920f4cb0e61ad90af7106b3de402f5fe127"},
+    {file = "watchdog-2.1.3-pp37-pypy37_pp73-macosx_10_9_x86_64.whl", hash = "sha256:b8ddb2c9f92e0c686ea77341dcb58216fa5ff7d5f992c7278ee8a392a06e86bb"},
+    {file = "watchdog-2.1.3-py3-none-manylinux2014_aarch64.whl", hash = "sha256:8805a5f468862daf1e4f4447b0ccf3acaff626eaa57fbb46d7960d1cf09f2e6d"},
+    {file = "watchdog-2.1.3-py3-none-manylinux2014_armv7l.whl", hash = "sha256:3e305ea2757f81d8ebd8559d1a944ed83e3ab1bdf68bcf16ec851b97c08dc035"},
+    {file = "watchdog-2.1.3-py3-none-manylinux2014_i686.whl", hash = "sha256:431a3ea70b20962e6dee65f0eeecd768cd3085ea613ccb9b53c8969de9f6ebd2"},
+    {file = "watchdog-2.1.3-py3-none-manylinux2014_ppc64.whl", hash = "sha256:e4929ac2aaa2e4f1a30a36751160be391911da463a8799460340901517298b13"},
+    {file = "watchdog-2.1.3-py3-none-manylinux2014_ppc64le.whl", hash = "sha256:201cadf0b8c11922f54ec97482f95b2aafca429c4c3a4bb869a14f3c20c32686"},
+    {file = "watchdog-2.1.3-py3-none-manylinux2014_s390x.whl", hash = "sha256:3a7d242a7963174684206093846537220ee37ba9986b824a326a8bb4ef329a33"},
+    {file = "watchdog-2.1.3-py3-none-manylinux2014_x86_64.whl", hash = "sha256:54e057727dd18bd01a3060dbf5104eb5a495ca26316487e0f32a394fd5fe725a"},
+    {file = "watchdog-2.1.3-py3-none-win32.whl", hash = "sha256:b5fc5c127bad6983eecf1ad117ab3418949f18af9c8758bd10158be3647298a9"},
+    {file = "watchdog-2.1.3-py3-none-win_amd64.whl", hash = "sha256:44acad6f642996a2b50bb9ce4fb3730dde08f23e79e20cd3d8e2a2076b730381"},
+    {file = "watchdog-2.1.3-py3-none-win_ia64.whl", hash = "sha256:0bcdf7b99b56a3ae069866c33d247c9994ffde91b620eaf0306b27e099bd1ae0"},
+    {file = "watchdog-2.1.3.tar.gz", hash = "sha256:e5236a8e8602ab6db4b873664c2d356c365ab3cac96fbdec4970ad616415dd45"},
+]
 zipp = [
     {file = "zipp-3.5.0-py3-none-any.whl", hash = "sha256:957cfda87797e389580cb8b9e3870841ca991e2125350677b2ca83a0e99390a3"},
     {file = "zipp-3.5.0.tar.gz", hash = "sha256:f5812b1e007e48cff63449a5e9f4e7ebea716b4111f9c4f9a645f91d579bf0c4"},

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "textual"
-version = "0.1.6"
+version = "0.1.7"
 homepage = "https://github.com/willmcgugan/textual"
 description = "Text User Interface using Rich"
 authors = ["Will McGugan <willmcgugan@gmail.com>"]
@@ -31,6 +31,9 @@ pytest = "^6.2.3"
 black = "^20.8b1"
 mypy = "^0.910"
 pytest-cov = "^2.12.1"
+mkdocs = "^1.2.1"
+mkdocstrings = "^0.15.2"
+mkdocs-material = "^7.1.10"
 
 [build-system]
 requires = ["poetry-core>=1.0.0"]

src/textual/app.py

@@ -23,7 +23,7 @@ from .binding import Bindings, NoBinding
 from .geometry import Point, Region
 from ._context import active_app
 from ._event_broker import extract_handler_actions, NoHandler
-from .keys import Binding
+from ._types import MessageTarget
 from .driver import Driver
 from .layouts.dock import DockLayout, Dock
 from ._linux_driver import LinuxDriver
@@ -56,6 +56,12 @@ ViewType = TypeVar("ViewType", bound=View)
 #     uvloop.install()
 
 
+class PanicMessage(Message):
+    def __init__(self, sender: MessageTarget, traceback: Traceback) -> None:
+        self.traceback = traceback
+        super().__init__(sender)
+
+
 class ActionError(Exception):
     pass
 
@@ -71,11 +77,19 @@ class App(MessagePump):
 
     def __init__(
         self,
-        console: Console = None,
+        console: Console | None = None,
         screen: bool = True,
-        driver_class: Type[Driver] = None,
+        driver_class: Type[Driver] | None = None,
         title: str = "Textual Application",
     ):
+        """The Textual Application base class
+
+        Args:
+            console (Console, optional): A Rich Console. Defaults to None.
+            screen (bool, optional): Enable full-screen application mode. Defaults to True.
+            driver_class (Type[Driver], optional): Driver class, or None to use default. Defaults to None.
+            title (str, optional): Title of the application. Defaults to "Textual Application".
+        """
         self.console = console or get_console()
         self._screen = screen
         self.driver_class = driver_class or LinuxDriver
@@ -88,6 +102,7 @@ class App(MessagePump):
         self.mouse_over: Widget | None = None
         self.mouse_captured: Widget | None = None
         self._driver: Driver | None = None
+        self._tracebacks: list[Traceback] = []
 
         self._docks: list[Dock] = []
         self._action_targets = {"app", "view"}
@@ -202,10 +217,12 @@ class App(MessagePump):
         if widget is not None:
             await widget.post_message(events.MouseCaptured(self, self.mouse_position))
 
+    def panic(self, traceback: Traceback) -> None:
+        self._tracebacks.append(traceback)
+        self.close_messages_no_wait()
+
     async def process_messages(self) -> None:
         log.debug("driver=%r", self.driver_class)
-        # loop = asyncio.get_event_loop()
-        # loop.add_signal_handler(signal.SIGINT, self.on_keyboard_interupt)
         driver = self._driver = self.driver_class(self.console, self)
         active_app.set(self)
 
@@ -242,10 +259,10 @@ class App(MessagePump):
                     view = self._view_stack.pop()
                     await view.close_messages()
             except Exception:
-                traceback = Traceback(show_locals=True)
+                self._tracebacks.append(Traceback(show_locals=True))
             finally:
                 driver.stop_application_mode()
-                if traceback is not None:
+                for traceback in self._tracebacks:
                     self.console.print(traceback)
 
     def require_repaint(self) -> None:
@@ -289,7 +306,7 @@ class App(MessagePump):
                 if sync_available:
                     console.file.write("\x1bP=2s\x1b\\")
             except Exception:
-                log.exception("refresh failed")
+                self.panic(Traceback(show_locals=True))
 
     def display(self, renderable: RenderableType) -> None:
         if not self._closed:

src/textual/layout.py

@@ -79,6 +79,16 @@ class Layout(ABC):
         self.height = 0
         self.renders: dict[Widget, tuple[Region, Lines]] = {}
         self._cuts: list[list[int]] | None = None
+        self._require_update: bool = True
+
+    def check_update(self) -> bool:
+        return self._require_update
+
+    def require_update(self) -> None:
+        self._require_update = True
+
+    def reset_update(self) -> None:
+        self._require_update = False
 
     def reset(self) -> None:
         self._cuts = None
@@ -265,10 +275,12 @@ class Layout(ABC):
     ) -> Iterable[list[Segment]]:
 
         for bucket in chops:
-            yield sum(
+            line: list[Segment] = []
-                (segments for _, segments in sorted(bucket.items()) if segments),
+            extend = line.extend
-                start=[],
+            for _, segments in sorted(bucket.items()):
-            )
+                if segments:
+                    extend(segments)
+            yield line
 
     def render(
         self,

src/textual/layouts/grid.py

@@ -9,7 +9,7 @@ import sys
 from typing import Iterable, NamedTuple
 
 from .._layout_resolve import layout_resolve
-from .._loop import loop_last
+
 from ..geometry import Dimensions, Point, Region
 from ..layout import Layout, OrderedRegion
 from ..view import View
@@ -80,17 +80,39 @@ class GridLayout(Layout):
 
         super().__init__()
 
-    def hide_row(self, row_name: str) -> None:
+    def is_row_visible(self, row_name: str) -> bool:
-        self.hidden_rows.add(row_name)
+        return row_name not in self.hidden_rows
 
-    def show_row(self, row_name: str) -> None:
+    def is_column_visible(self, column_name: str) -> bool:
-        self.hidden_rows.discard(row_name)
+        return column_name not in self.hidden_columns
 
-    def hide_column(self, column_name: str) -> None:
+    def show_row(self, row_name: str, visible: bool = True) -> bool:
-        self.hidden_rows.add(column_name)
+        changed = False
+        if visible:
+            if not self.is_row_visible(row_name):
+                self.require_update()
+                changed = True
+            self.hidden_rows.discard(row_name)
+        else:
+            if self.is_row_visible(row_name):
+                self.require_update()
+                changed = True
+            self.hidden_rows.add(row_name)
+        return changed
 
-    def show_column(self, column_name: str) -> None:
+    def show_column(self, column_name: str, visible: bool = True) -> bool:
-        self.hidden_rows.discard(column_name)
+        changed = False
+        if visible:
+            if not self.is_column_visible(column_name):
+                self.require_update()
+                changed = True
+            self.hidden_rows.discard(column_name)
+        else:
+            if self.is_column_visible(column_name):
+                self.require_update()
+                changed = True
+            self.hidden_rows.add(column_name)
+        return changed
 
     def add_column(
         self,

src/textual/message.py

@@ -27,7 +27,7 @@ class Message:
         self.name = camel_to_snake(self.__class__.__name__.replace("Message", ""))
         self.time = monotonic()
         self._no_default_action = False
-        self._stop_propagaton = False
+        self._stop_propagation = False
         super().__init__()
 
     def __rich_repr__(self) -> rich.repr.RichReprResult:
@@ -57,5 +57,5 @@ class Message:
         """
         self._no_default_action = prevent
 
-    def stop_propagation(self, stop: bool = True) -> None:
+    def stop(self, stop: bool = True) -> None:
-        self._stop_propagaton = stop
+        self._stop_propagation = stop

src/textual/message_pump.py

@@ -1,19 +1,28 @@
 from __future__ import annotations
 
 import asyncio
+from asyncio import CancelledError
+from functools import partial
 import logging
-from asyncio import Event, Queue, QueueEmpty, Task
+from asyncio import Queue, QueueEmpty, Task
-from typing import Any, Awaitable, Coroutine, NamedTuple
+from typing import TYPE_CHECKING, Awaitable, Iterable, Callable
 from weakref import WeakSet
 
+from rich.traceback import Traceback
+
 from . import events
 from ._timer import Timer, TimerCallback
 from ._types import MessageHandler
+from ._context import active_app
 from .message import Message
 
 log = logging.getLogger("rich")
 
 
+if TYPE_CHECKING:
+    from .app import App
+
+
 class NoParent(Exception):
     pass
 
@@ -44,6 +53,15 @@ class MessagePump:
             raise NoParent(f"{self._parent} has no parent")
         return self._parent
 
+    @property
+    def app(self) -> "App":
+        """Get the current app."""
+        return active_app.get()
+
+    @property
+    def is_parent_active(self):
+        return self._parent and not self._parent._closed and not self._parent._closing
+
     def set_parent(self, parent: MessagePump) -> None:
         self._parent = parent
 
@@ -120,6 +138,9 @@ class MessagePump:
         self._child_tasks.add(asyncio.get_event_loop().create_task(timer.run()))
         return timer
 
+    def close_messages_no_wait(self) -> None:
+        self._message_queue.put_nowait(None)
+
     async def close_messages(self, wait: bool = True) -> None:
         """Close message queue, and optionally wait for queue to finish processing."""
         if self._closed:
@@ -138,12 +159,20 @@ class MessagePump:
         self._task = asyncio.create_task(self.process_messages())
 
     async def process_messages(self) -> None:
+        try:
+            return await self._process_messages()
+        except CancelledError:
+            pass
+
+    async def _process_messages(self) -> None:
         """Process messages until the queue is closed."""
         while not self._closed:
             try:
                 message = await self.get_message()
             except MessagePumpClosed:
                 break
+            except CancelledError:
+                raise
             except Exception as error:
                 log.exception("error in get_message()")
                 raise error from None
@@ -161,9 +190,11 @@ class MessagePump:
 
             try:
                 await self.dispatch_message(message)
-            except Exception as error:
+            except CancelledError:
-                log.exception("error in dispatch_message")
                 raise
+            except Exception as error:
+                self.app.panic(Traceback(show_locals=True))
+                break
             finally:
                 if isinstance(message, events.Event) and self._message_queue.empty():
                     if not self._closed:
@@ -182,25 +213,39 @@ class MessagePump:
             return await self.on_message(message)
         return False
 
-    async def on_event(self, event: events.Event) -> None:
+    def _get_dispatch_methods(
-        method_name = f"on_{event.name}"
+        self, method_name: str, message: Message
+    ) -> Iterable[Callable[[Message], Awaitable]]:
+        for cls in self.__class__.__mro__:
+            if message._no_default_action:
+                break
+            method = getattr(cls, method_name, None)
+            if method is not None:
+                yield method.__get__(self, cls)
 
-        dispatch_function: MessageHandler = getattr(self, method_name, None)
+    async def on_event(self, event: events.Event) -> None:
-        if dispatch_function is not None:
+        _rich_traceback_guard = True
-            await dispatch_function(event)
+
-        if event.bubble and self._parent and not event._stop_propagaton:
+        for method in self._get_dispatch_methods(f"on_{event.name}", event):
-            if event.sender == self._parent:
+            await method(event)
-                pass
+
-                # log.debug("bubbled event abandoned; %r", event)
+        if event.bubble and self._parent and not event._stop_propagation:
-            elif not self._parent._closed and not self._parent._closing:
+            if event.sender != self._parent and self.is_parent_active:
                 await self._parent.post_message(event)
 
     async def on_message(self, message: Message) -> None:
+        _rich_traceback_guard = True
         method_name = f"message_{message.name}"
-        method = getattr(self, method_name, None)
+
-        if method is not None:
+        for method in self._get_dispatch_methods(method_name, message):
             await method(message)
 
+        if message.bubble and self._parent and not message._stop_propagation:
+            if message.sender == self._parent:
+                pass
+            elif not self._parent._closed and not self._parent._closing:
+                await self._parent.post_message(message)
+
     def post_message_no_wait(self, message: Message) -> bool:
         if self._closing or self._closed:
             return False

src/textual/page.py

@@ -7,7 +7,6 @@ from rich.padding import Padding, PaddingDimensions
 from rich.segment import Segment
 from rich.style import StyleType
 
-from . import events
 from .geometry import Dimensions, Point
 from .message import Message
 from .widget import Widget, Reactive
@@ -56,7 +55,6 @@ class PageRender:
 
     def render(self, console: Console, options: ConsoleOptions) -> None:
         width = self.width or options.max_width or console.width
-        width *= 2
         options = options.update_dimensions(width, None)
         style = console.get_style(self.style)
         renderable = self.renderable

src/textual/scrollbar.py

@@ -152,7 +152,6 @@ class ScrollBarRender:
     def __rich_console__(
         self, console: Console, options: ConsoleOptions
     ) -> RenderResult:
-        log.debug("SCROLLBAR RENDER")
         size = (
             (options.height or console.height)
             if self.vertical
@@ -231,7 +230,6 @@ class ScrollBar(Widget):
     async def on_mouse_up(self, event: events.MouseUp) -> None:
         if self.grabbed:
             await self.release_mouse()
-        await super().on_mouse_up(event)
 
     async def on_mouse_captured(self, event: events.MouseCaptured) -> None:
         self.grabbed = event.mouse_position

src/textual/view.py

@@ -44,6 +44,9 @@ class View(Widget):
     def __rich_repr__(self) -> rich.repr.RichReprResult:
         yield "name", self.name
 
+    def __getitem__(self, widget_name: str) -> Widget:
+        return self.named_widgets[widget_name]
+
     @property
     def is_visual(self) -> bool:
         return False

src/textual/widget.py

@@ -87,11 +87,6 @@ class Widget(MessagePump):
     def is_visual(self) -> bool:
         return True
 
-    @property
-    def app(self) -> "App":
-        """Get the current app."""
-        return active_app.get()
-
     @property
     def console(self) -> Console:
         """Get the current console."""

src/textual/widgets/_button.py

@@ -7,10 +7,16 @@ from rich.panel import Panel
 import rich.repr
 from rich.style import StyleType
 
+from .. import events
+from ..message import Message
 from ..reactive import Reactive
 from ..widget import Widget
 
 
+class ButtonPressed(Message, bubble=True):
+    pass
+
+
 class Expand:
     def __init__(self, renderable: RenderableType) -> None:
         self.renderable = renderable
@@ -48,11 +54,15 @@ class Button(Widget):
         name: str | None = None,
         style: StyleType = "white on dark_blue",
     ):
-        self.label = label
         self.name = name or str(label)
         self.style = style
-        super().__init__()
+        super().__init__(name=name)
+        self.label = label
+
+    label: Reactive[RenderableType] = Reactive("")
 
     def render(self) -> RenderableType:
         return ButtonRenderable(self.label, style=self.style)
-        return Align.center(self.label, vertical="middle", style=self.style)
+
+    async def on_click(self, event: events.Click) -> None:
+        await self.emit(ButtonPressed(self))

src/textual/widgets/_scroll_view.py

@@ -29,18 +29,19 @@ class ScrollView(View):
         fluid: bool = True,
     ) -> None:
         self.fluid = fluid
-        self._vertical_scrollbar = ScrollBar(vertical=True)
+        self.vscroll = ScrollBar(vertical=True)
-        self._horizontal_scrollbar = ScrollBar(vertical=False)
+        self.hscroll = ScrollBar(vertical=False)
-        self._page = Page(renderable or "", style=style)
+        self.page = Page(renderable or "", style=style)
         layout = GridLayout()
         layout.add_column("main")
-        layout.add_column("vertical", size=1)
+        layout.add_column("vscroll", size=1)
         layout.add_row("main")
-        layout.add_row("horizontal", size=1)
+        layout.add_row("hscroll", size=1)
         layout.add_areas(
-            content="main,main", vertical="vertical,main", horizontal="main,horizontal"
+            content="main,main", vscroll="vscroll,main", hscroll="main,hscroll"
         )
-        # layout.hide_row("horizontal")
+        layout.show_row("hscroll", False)
+        layout.show_row("vscroll", False)
         super().__init__(name=name, layout=layout)
 
     x: Reactive[float] = Reactive(0)
@@ -50,35 +51,35 @@ class ScrollView(View):
     target_y: Reactive[float] = Reactive(0)
 
     def validate_x(self, value: float) -> float:
-        return clamp(value, 0, self._page.contents_size.width - self.size.width)
+        return clamp(value, 0, self.page.contents_size.width - self.size.width)
 
     def validate_target_x(self, value: float) -> float:
-        return clamp(value, 0, self._page.contents_size.width - self.size.width)
+        return clamp(value, 0, self.page.contents_size.width - self.size.width)
 
     def validate_y(self, value: float) -> float:
-        return clamp(value, 0, self._page.contents_size.height - self.size.height)
+        return clamp(value, 0, self.page.contents_size.height - self.size.height)
 
     def validate_target_y(self, value: float) -> float:
-        return clamp(value, 0, self._page.contents_size.height - self.size.height)
+        return clamp(value, 0, self.page.contents_size.height - self.size.height)
 
     async def watch_x(self, new_value: float) -> None:
-        self._page.x = round(new_value)
+        self.page.x = round(new_value)
-        self._horizontal_scrollbar.position = round(new_value)
+        self.hscroll.position = round(new_value)
 
     async def watch_y(self, new_value: float) -> None:
-        self._page.y = round(new_value)
+        self.page.y = round(new_value)
-        self._vertical_scrollbar.position = round(new_value)
+        self.vscroll.position = round(new_value)
 
     async def update(self, renderabe: RenderableType) -> None:
-        self._page.update(renderabe)
+        self.page.update(renderabe)
         self.require_repaint()
 
     async def on_mount(self, event: events.Mount) -> None:
         assert isinstance(self.layout, GridLayout)
         self.layout.place(
-            content=self._page,
+            content=self.page,
-            vertical=self._vertical_scrollbar,
+            vscroll=self.vscroll,
-            horizontal=self._horizontal_scrollbar,
+            hscroll=self.hscroll,
         )
         await self.layout.mount_all(self)
 
@@ -133,7 +134,7 @@ class ScrollView(View):
 
     async def key_end(self) -> None:
         self.target_x = 0
-        self.target_y = self._page.contents_size.height - self.size.height
+        self.target_y = self.page.contents_size.height - self.size.height
         self.animate("x", self.target_x, duration=1, easing="out_cubic")
         self.animate("y", self.target_y, duration=1, easing="out_cubic")
 
@@ -146,7 +147,7 @@ class ScrollView(View):
     async def on_resize(self, event: events.Resize) -> None:
         await super().on_resize(event)
         if self.fluid:
-            self._page.update()
+            self.page.update()
 
     async def message_scroll_up(self, message: Message) -> None:
         self.page_up()
@@ -171,7 +172,17 @@ class ScrollView(View):
     async def message_page_update(self, message: Message) -> None:
         self.x = self.validate_x(self.x)
         self.y = self.validate_y(self.y)
-        self._horizontal_scrollbar.virtual_size = self._page.virtual_size.width
+        self.vscroll.virtual_size = self.page.virtual_size.height
-        self._horizontal_scrollbar.window_size = self.size.width
+        self.vscroll.window_size = self.size.height
-        self._vertical_scrollbar.virtual_size = self._page.virtual_size.height
+        if self.layout.show_column(
-        self._vertical_scrollbar.window_size = self.size.height
+            "vscroll", self.page.virtual_size.height > self.size.height
+        ):
+            self.page.update()
+
+        self.hscroll.virtual_size = self.page.virtual_size.width
+        self.hscroll.window_size = self.size.width
+
+        if self.layout.show_row(
+            "hscroll", self.page.virtual_size.width > self.size.width
+        ):
+            self.page.update()