textology 0.3.5

Textual extensions for creating Terminal User Interfaces

---

Textology

The study of making interactive UIs with text.

Why should GUIs have all the fun? Textology helps create TUIs by extending the amazing functionality of Textual and Rich, with design principles from other well known libraries and frameworks.

Commonly known as Text (or Terminal) User Interfaces, the goal of a TUI (Tooey) is to provide as close as possible to a traditional GUI experience straight from a terminal. Why? Not all environments allow full graphical library access, web access, etc., but almost all provide access from a terminal. Yes, even terminals can provide mouse support, sophisticated layouts, animations, and a wide range of colors!

Like Textual, Textology is inspired by modern web development. Textology extends Textual by bringing together, and expanding upon, designs from other frameworks such as Dash/FastAPI/Flask, including their use of routing, annotations, and observation patterns. Why? To increase developer velocity based on existing experience. Textology also receives inspiration from other UI frameworks external to Python, such as iOS, Android, and Web frameworks. Most importantly however, Textology is an extension of Textual: it does not replace Textual, but rather provides additional options on top of the core framework.

Before using Textology, be comfortable with Textual. For tutorials, guides, etc., refer to the Textual Documentation. Textology is NOT a replacement for Textual, it is an extension. Callbacks, widgets, screens, event lifecycles, etc., from Textual still apply to Textology extended widgets and applications. For other advanced features, familiarity with Dash/FastAPI/Flask principles will help. Examples for Textology extensions, such as callback based applications, are included in this documentation.

Table Of Contents

• Compatibility
• Key Features
• Getting Started
  • Installation
  • Extended Applications
  • Extended Widgets
  • Extended Testing

Compatibility

Textology follows Textual Compatibility guidelines with one exception: Python3.10 minimum requirement.

Top Features

• Extended basic widgets, such as:
  • Buttons with ability to declare callbacks inline, and track click counts
  • ListItems with metadata objects and ability to disable event messages
• New widgets, such as:
  • ListItemHeaders (non-interactive ListItems)
  • HorizontalMenus (walkable list of ListViews with peeking at following lists)
• Extended apps, with "event driven architecture"/"observation pattern" to detect changes and automatically update UI.
  • Listen to reactive attribute changes.
  • Listen to posted events/messages.
• Enhanced testing support
  • Parallel tests via python-xdist
  • Custom testing arguments, such as updating snapshots on failures
• Multiple theme support
  • Swap CSS themes live
  • Apply multiple CSS themes simultaneously

Getting Started

Installation

Install Textology via pip:

pip install textology

For development of applications based on Textual/Textology (but not development of Textology itself), use the [dev] package. This installs extra Textual development tools, and requirements for Textology testing extensions.

pip install textology[dev]

For full development of Textology itself, use the [full-dev] package. This installs Textual development tools, requirements for Textology testing extensions, and full QA requirements to meet commit standards. This version has the highest library requirements, in order to match the versions used by Textology itself for testing. Required if developing Textology itself, or recommended if looking to match/exceed the level of QA testing used by Textology.

pip install textology[full-dev]

Extended Applications

Textology app classes, such as ExtendedApp, can replace any regular Textual App, and be used as is without any extensions turned on. Here is an example of the most commonly used application subclass, ExtendedApp, and its primary extended functionality being used. More detailed examples of applications based around routes, callbacks, and standard Textual applications can be found in Examples.

• Observer/callback application (automatic attribute monitoring and updates by element IDs without manual queries):

from textology.apps import ExtendedApp
from textology.observers import Modified, Select, Update
from textology.widgets import Button, Container, Label

app = ExtendedApp(
    layout=Container(
        Button("Ping", id="ping-btn"),
        Button("Pong", id="pong-btn"),
        Button("Sing-a-long", id="sing-btn"),
        Container(
            id="content",
        ),
    )
)


@app.when(
    Modified("ping-btn", "n_clicks"),
    Update("content", "children"),
)
def ping(clicks):
    return Label(f"Ping pressed {clicks}")


@app.when(
    Modified("pong-btn", "n_clicks"),
    Update("content", "children"),
)
def pong(clicks):
    return Label(f"Pong pressed {clicks}")


@app.when(
    Modified("sing-btn", "n_clicks"),
    Select("ping-btn", "n_clicks"),
    Select("pong-btn", "n_clicks"),
    Update("content", "children"),
)
def song(song_clicks, ping_clicks, pong_clicks):
    if not ping_clicks or not pong_clicks:
        return Label(f"Press Ping and Pong first to complete the song!")
    return Label(f"Ping, pong, sing-a-long song pressed {song_clicks}")


app.run()

• Callbacks can also be async:

@app.when(
    Modified("pong-btn", "n_clicks"),
    Update("content", "children"),
)
async def delayed_pong(clicks):
    await asyncio.sleep(3)
    return Label(f"Pong pressed {clicks} and updated 3 seconds later")

• Callbacks can also catch Exceptions from other callbacks:

@app.when(
    Raised(Exception),
)
def error_notification(error):
    app.notify(f"An unknown error occurred: {error}", title="Error")

• Callbacks can also listen for stateless events, not just stateful attribute updates

  from textology.apps import ExtendedApp
  from textology.observers import Published, Select, Update
  from textology.widgets import Button, Container, Label
  
  app = ExtendedApp(
      layout=Container(
          Button("Ping", id="ping-btn"),
          Button("Pong", id="pong-btn"),
          Button("Sing-a-long", id="sing-btn"),
          Container(
              id="content",
          ),
      )
  )
  
  @app.when(
      Published("ping-btn", Button.Pressed),
      Update("content", "children"),
  )
  def ping(event):
      return Label(f"Ping pressed {event.button.n_clicks}")
  
  @app.when(
      Published("pong-btn", Button.Pressed),
      Update("content", "children"),
  )
  def pong(event):
      return Label(f"Pong pressed {event.button.n_clicks}")
  
  @app.when(
      Published("sing-btn", Button.Pressed),
      Select("ping-btn", "n_clicks"),
      Select("pong-btn", "n_clicks"),
      Update("content", "children"),
  )
  def song(event, ping_clicks, pong_clicks):
      if not ping_clicks or not pong_clicks:
          return Label(f"Press Ping and Pong first to complete the song!")
      return Label(f"Ping, pong, sing-a-long song pressed {event.button.n_clicks}")
  
  app.run()
  

• Callbacks can also be registered on methods, to share across all application instances

  from textology.apps import ExtendedApp
  from textology.observers import Published, Select, Update, when
  from textology.widgets import Button, Container, Label
  
  
  class Page(Container):
      def compose(self):
          yield Button("Ping", id="ping-btn")
          yield Button("Pong", id="pong-btn")
          yield Button("Sing-a-long", id="sing-btn")
          yield Container(
              id="content",
          )
  
      @when(
          Published("ping-btn", Button.Pressed),
          Update("content", "children"),
      )
      def ping(self, event):
          return Label(f"Ping pressed {event.button.n_clicks}")
  
      @when(
          Published("pong-btn", Button.Pressed),
          Update("content", "children"),
      )
      def pong(self, event):
          return Label(f"Pong pressed {event.button.n_clicks}")
  
      @when(
          Published("sing-btn", Button.Pressed),
          Select("ping-btn", "n_clicks"),
          Select("pong-btn", "n_clicks"),
          Update("content", "children"),
      )
      def song(self, event, ping_clicks, pong_clicks):
          if not ping_clicks or not pong_clicks:
              return Label(f"Press Ping and Pong first to complete the song!")
          return Label(f"Ping, pong, sing-a-long song pressed {event.button.n_clicks}")
  
  
  app = ExtendedApp(
      layout=Page()
  )
  
  app.run()
  

• Callbacks can also use Dash code style (Same as others, but with Dash compatibility object and calls)

  from textology.dash_compat import DashCompatApp, Input, Output, State
  from textology.widgets import Button, Container, Label
  
  app = DashCompatApp(
      layout=Container(
          Button("Ping", id="ping-btn"),
          Button("Pong", id="pong-btn"),
          Button("Sing-a-long", id="sing-btn"),
          Container(
              id="content",
          ),
      )
  )
  
  @app.callback(
      Input("ping-btn", "n_clicks"),
      Output("content", "children"),
  )
  def ping(clicks):
      return Label(f"Ping pressed {clicks}")
  
  @app.callback(
      Input("pong-btn", "n_clicks"),
      Output("content", "children"),
  )
  def pong(clicks):
      return Label(f"Pong pressed {clicks}")
  
  @app.callback(
      Input("sing-btn", "n_clicks"),
      State("ping-btn", "n_clicks"),
      State("pong-btn", "n_clicks"),
      Output("content", "children"),
  )
  def song(song_clicks, ping_clicks, pong_clicks):
      if not ping_clicks or not pong_clicks:
          return Label(f"Press Ping and Pong first to complete the song!")
      return Label(f"Ping, pong, sing-a-long song pressed {song_clicks}")
  
  app.run()
  

Extended Widgets

Native Textual widgets can be directly swapped out with Textology extended equivalents. They can then be used as is (standard Textual usage), or with extensions (via extra keyword arguments).

• Basic swap (no extensions):

# Replace:
from textual.widgets import Button

# With:
from textology.widgets import Button

• Instance callback extension (avoid global watchers, name/ID checks in the event watchers, and event chaining):

from textology.widgets import Button

def on_click(event):
    print("Don't press my buttons...")

button = Button(
    callbacks={"on_button_pressed": on_click},
)

• Instance style extension (set styles directly at instantiation based on logic):

from textology.widgets import Button

feeling_blue = True

button = Button(
    styles={
        "background": "blue" if feeling_blue else "green",
    },
)

• Instance message disable extension (avoid unused event chains, such as in large ListViews):

from textual import events
from textology.widgets import ListItem

item = ListItem(
    disabled_messages=[events.Mount, events.Show],
)

Extended Testing

Don't want to serialize your pytests? Looking for the ability to quickly visualize differences when UIs change? You came to the right place. Textology extends Textual SVG snapshot capabilities to add support for parallel processing during tests (python-xdist), and custom options such as auto updating SVG snapshots on failures. In order to use the pytest extensions automagically, add the following to a conftest.py in the root of the project. This will enable usage of the compare_snapshots fixture, and HTML report generation on failure, automatically.

pytest_plugins = ("textology.pytest_utils",)

• Basic snapshot test:

import pytest
from textual import App
from textual.widgets import Button

class BasicApp(App):
    def compose(self):
        yield Button("Click me!")

@pytest.mark.asyncio
async def test_snapshot_with_app(compare_snapshots):
    assert await compare_snapshots(BasicApp())

Other advanced testing features include:

• Ability to pass an App, App Pilot, or a module containing an instantiated App or Pilot, to fixtures
• Custom snapshot paths, including reusing the same snapshot across multiple tests
• Automatic SVG updates with pytest --txtology-snap-update

View all options by running pytest -h and referring to Custom options: section.