Log

Added in version 0.32.0

A Log widget displays lines of text which may be appended to in realtime.

Call Log.write_line to write a line at a time, or Log.write_lines to write multiple lines at once. Call Log.clear to clear the Log widget.

Tip

See also RichLog which can write more than just text, and supports a number of advanced features.

• Focusable
• Container

Example

The example below shows how to write text to a Log widget:

Outputlog.py

from textual.app import App, ComposeResult
from textual.widgets import Log

TEXT = """I must not fear.
Fear is the mind-killer.
Fear is the little-death that brings total obliteration.
I will face my fear.
I will permit it to pass over me and through me.
And when it has gone past, I will turn the inner eye to see its path.
Where the fear has gone there will be nothing. Only I will remain."""


class LogApp(App):
    """An app with a simple log."""

    def compose(self) -> ComposeResult:
        yield Log()

    def on_ready(self) -> None:
        log = self.query_one(Log)
        log.write_line("Hello, World!")
        for _ in range(10):
            log.write_line(TEXT)


if __name__ == "__main__":
    app = LogApp()
    app.run()

Reactive Attributes

Name	Type	Default	Description
max_lines	int	None	Maximum number of lines in the log or None for no maximum.
auto_scroll	bool	False	Scroll to end of log when new lines are added.

Messages

This widget posts no messages.

Bindings

This widget has no bindings.

Component Classes

This widget has no component classes.

---

textual.widgets.Log class

def __init__(
    self,
    highlight=False,
    max_lines=None,
    auto_scroll=True,
    name=None,
    id=None,
    classes=None,
    disabled=False,
):

Bases: ScrollView

A widget to log text.

Parameters

Parameter	Default	Description
highlight bool	False	Enable highlighting.
max_lines int | None	None	Maximum number of lines to display.
auto_scroll bool	True	Scroll to end on new lines.
name str | None	None	The name of the text log.
id str | None	None	The ID of the text log in the DOM.
classes str | None	None	The CSS classes of the text log.
disabled bool	False	Whether the text log is disabled or not.

auto_scroll instance-attribute class-attribute

auto_scroll: var[bool] = auto_scroll

Automatically scroll to new lines.

highlight instance-attribute

highlight = highlight

Enable highlighting.

highlighter instance-attribute

highlighter = ReprHighlighter()

The Rich Highlighter object to use, if highlight=True

line_count property

line_count: int

Number of lines of content.

lines property

lines: Sequence[str]

The raw lines in the Log.

Note that this attribute is read only. Changing the lines will not update the Log's contents.

max_lines instance-attribute class-attribute

max_lines: var[int | None] = max_lines

Maximum number of lines to show

clear method

def clear(self):

Clear the Log.

Returns

Type	Description
Self	The Log instance.

notify_style_update method

def notify_style_update(self):

Called by Textual when styles update.

refresh_lines method

def refresh_lines(self, y_start, line_count=1):

Refresh one or more lines.

Parameters

Parameter	Default	Description
y_start int	required	First line to refresh.
line_count int	1	Total number of lines to refresh.

write method

def write(self, data, scroll_end=None):

Write to the log.

Parameters

Parameter	Default	Description
data str	required	Data to write.
scroll_end bool | None	None	Scroll to the end after writing, or None to use self.auto_scroll.

Returns

Type	Description
Self	The Log instance.

write_line method

def write_line(self, line):

Write content on a new line.

Parameters

Parameter	Default	Description
line str	required	String to write to the log.

Returns

Type	Description
Self	The Log instance.

write_lines method

def write_lines(self, lines, scroll_end=None):

Write an iterable of lines.

Parameters

Parameter	Default	Description
lines Iterable[str]	required	An iterable of strings to write.
scroll_end bool | None	None	Scroll to the end after writing, or None to use self.auto_scroll.

Returns

Type	Description
Self	The Log instance.