# Properties

editor-visible, validated, range-bounded node values.

```{raw} html
<a class="example-run-button" href="../demos/features_basics_properties.html">▶ Run in browser</a>

```

**Tags:** `basics` `property` `inspector`

A `Property` is a descriptor declared as a class attribute. It gives a node a
typed value the editor inspector can show and the scene serializer persists,
with automatic range clamping and an optional `on_change` hook. Here two bars
are driven entirely by their `Property` values: drag-free sliders animate the
values, the renderer reads them back, and an out-of-range write is clamped in
place so the drawing never exceeds its bounds.


## What it demonstrates

- `Property(default, range=(lo, hi))` -- a class attribute holding a validated value, read/written via `self.attr`.
- Range clamping: assigning outside `(lo, hi)` silently clamps to the nearest bound (no exception).
- `Property(default, on_change="method")` -- a bound method fires only when the value actually changes.
- Property values driving what a node draws each frame.

## Source

```{literalinclude} ../../examples/features/basics/properties.py
:language: python
:linenos:
```