QtPie

Tasty way to build Qt apps

from qtpie import entrypoint, make, state, widget
from qtpy.QtWidgets import QLabel, QPushButton, QWidget


@entrypoint
@widget
class Counter(QWidget):
    count: int = state(0)
    label: QLabel = make(QLabel, bind="Count: {count}")
    button: QPushButton = make(QPushButton, "+1", clicked="increment")

    def increment(self) -> None:
        self.count += 1

Click the button. State changes. Label updates. That's it.

Declarative. Reactive. Delightful.

Install

pip install qtpie

Features

• state() - reactive variables that update the UI
• bind="{x}" - format expressions with auto-refresh
• clicked="method" - signal connections by name
• @widget - dataclass-style components with automatic layouts
• Widget[T] - type-safe model binding
• SCSS hot reload - style with CSS classes
• Async support - async def just works
• pyright strict - full type safety, no compromises

Why QtPie?

Qt is powerful but verbose:

# Plain Qt - 35 lines of boilerplate
class Counter(QWidget):
    def __init__(self):
        super().__init__()
        self.setObjectName("Counter")
        self.count = 0

        layout = QVBoxLayout(self)

        self.label = QLabel("Count: 0")
        self.label.setObjectName("label")
        layout.addWidget(self.label)

        self.button = QPushButton("Add")
        self.button.setObjectName("button")
        self.button.clicked.connect(self.increment)
        layout.addWidget(self.button)

    def increment(self):
        self.count += 1
        self.label.setText(f"Count: {self.count}")


if __name__ == "__main__":
    app = QApplication([])
    window = Counter()
    window.show()
    app.exec()

vs QtPie - 12 lines, fully reactive:

@entrypoint
@widget
class Counter(QWidget):
    count: int = state(0)
    label: QLabel = make(QLabel, bind="Count: {count}")
    button: QPushButton = make(QPushButton, "+1", clicked="increment")

    def increment(self) -> None:
        self.count += 1

Quick Examples

Reactive State

count: int = state(0)
label: QLabel = make(QLabel, bind="Count: {count}")

self.count += 1  # Label updates instantly

Two-Way Binding

@widget
class Greeter(QWidget):
    name: str = state("")
    name_input: QLineEdit = make(QLineEdit, bind="name")
    greeting: QLabel = make(QLabel, bind="Hello, {name}!")

Type in the input, greeting updates. Change self.name, input updates.

Format Expressions

bind="Count: {count}"
bind="{first} {last}"
bind="{name.upper()}"
bind="Total: ${price * 1.1:.2f}"

Automatic Layouts

@widget
class MyWidget(QWidget):
    top: QLabel = make(QLabel, "Top")
    middle: QLabel = make(QLabel, "Middle")
    bottom: QLabel = make(QLabel, "Bottom")

@widget(layout="form")
class MyForm(QWidget):
    name: QLineEdit = make(QLineEdit, form_label="Name:")
    email: QLineEdit = make(QLineEdit, form_label="Email:")

Model Binding

@dataclass
class Person:
    name: str = ""
    age: int = 0

@widget
class PersonEditor(QWidget, Widget[Person]):
    name: QLineEdit = make(QLineEdit)  # auto-binds to model.name
    age: QSpinBox = make(QSpinBox)      # auto-binds to model.age

Full Qt Access

QtPie is a layer, not a cage. All of Qt is still there:

@widget
class MyWidget(QWidget):
    label: QLabel = make(QLabel, "Hello")

    def setup(self) -> None:
        self.setWindowTitle("My App")
        self.label.setStyleSheet("color: red;")

Documentation

https://mrowrlib.github.io/qtpie

License

0BSD