Param: Declarative Parameters

Create typed, validated class attributes with reactive programming support.

Hello World Example

# DO always add this to ignore pyright Parameter type annotation warnings
# pyright: reportAssignmentType=false
import param

class Greeter(param.Parameterized):
    """A greeting generator with history tracking."""

    # DON'T use 'name' as parameter - it's reserved in Param
    # DO add type annotations, defaults, and doc strings
    target: str = param.String(default="World", doc="Name to greet")
    greeting: str = param.Selector(default="Hello", objects=["Hello", "Hi", "Hey"])
    count: int = param.Integer(default=1, bounds=(1, 10), doc="Repetitions")