RQComputedList

example code

import random
import sys

from PyQt5.QtCore import pyqtSlot
from PyQt5.QtWidgets import QApplication, QMainWindow, QVBoxLayout, QWidget, QLabel, QPushButton

from pyreaqtive.layouts import RQHBoxLayout
from pyreaqtive.models import RQList, RQModel, RQComputedList


class Number(RQModel):

    def __init__(self):
        super(Number, self).__init__()
        self.number = random.randint(0, 100)

    @property
    def is_odd(self):
        return self.number % 2 != 0


class ItemWidget(QWidget):

    def __init__(self, model: Number, list_model: RQList):
        super().__init__()

        self.model = model
        self.list_model = list_model

        self.main_layout = QVBoxLayout(self)
        self.resize(200, 200)

        self.number_label = QLabel(f"{model.number}")
        self.main_layout.addWidget(self.number_label)


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        widget = QWidget()
        layout = QVBoxLayout()
        widget.setLayout(layout)
        self.setCentralWidget(widget)

        self.all_numbers = RQList()

        self.odd_numbers = RQComputedList(
            lambda numbers: sorted(
                [number for number in numbers if number.is_odd],
                key=lambda number: number.number
            ),
            numbers=self.all_numbers
        )
        self.even_numbers = RQComputedList(
            lambda numbers: sorted(
                [number for number in numbers if not number.is_odd],
                key=lambda number: number.number
            ),
            numbers=self.all_numbers
        )

        self.add_button = QPushButton("Add")
        self.add_button.clicked.connect(self.add_item)
        layout.addWidget(self.add_button)

        layout.addWidget(QLabel("all numbers"))
        all_numbers_display = RQHBoxLayout(
            model=self.all_numbers,
            widget=self.widget_callback
        )
        layout.addLayout(all_numbers_display)

        layout.addWidget(QLabel("odd numbers"))
        odd_numbers_display = RQHBoxLayout(
            model=self.odd_numbers,
            widget=ItemWidget
        )
        layout.addLayout(odd_numbers_display)

        layout.addWidget(QLabel("even numbers"))
        even_numbers = RQHBoxLayout(
            model=self.even_numbers,
            widget=ItemWidget
        )
        layout.addLayout(even_numbers)

    def widget_callback(self, model: RQModel, list: RQList) -> QLabel:
        if not isinstance(model, Number):
            raise TypeError

        return QLabel(f"{model.number}")

    @pyqtSlot()
    def add_item(self):
        self.all_numbers.append(
            Number()
        )


app = QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec()