qt-signals-slots

Signals and Slots

Defining Custom Signals

Python/PySide6 and PyQt6:

from PySide6.QtCore import QObject, Signal

class DataProcessor(QObject):
    # Class-level signal declarations — NOT instance attributes
    processing_started = Signal()
    data_ready = Signal(list)          # carries a list
    progress_updated = Signal(int)     # carries an int (0–100)
    error_occurred = Signal(str)       # carries an error message
    result_ready = Signal(object)      # carries any Python object

    def process(self, data: list) -> None:
        self.processing_started.emit()
        # ... processing ...