9.7. Tkinter Integration

Wire a ComponentVMOf[M] to a Tkinter widget through StringVar, IntVar, and friends. Tkinter is included with CPython — no extra dependency.

9.7.1. Reactivity primitive

Tkinter variables (StringVar, IntVar, BooleanVar, DoubleVar) are observable: any widget bound via textvariable= re-renders when the variable's .set(value) is called. There is no collection observable; lists need to be re-applied to a Listbox.

9.7.2. Mapping

Tkinter	VMx
StringVar.set(x)	PropertyChangedMessage[str] handler
tk.Button(command=fn)	command.execute(None) inside fn
Listbox.insert / delete	CollectionChangedMessage handler
widget.after(...)	RxDispatcher.asyncio(loop) (or run-loop bridge)

9.7.3. Adapter skeleton

from collections.abc import Callable

import tkinter as tk
import reactivex.operators as ops
from vmx import ComponentVMOf, Message, MessageHubProto, PropertyChangedMessage, RelayCommand

def bind_string(var: tk.StringVar, vm: ComponentVMOf[Note],
                hub: MessageHubProto[Message], property_name: str = "model"
                ) -> Callable[[], None]:
    var.set(vm.model.title)

    def _on_msg(msg: PropertyChangedMessage[object]) -> None:
        if msg.property_name == property_name:
            var.set(vm.model.title)

    sub = hub.messages.pipe(
        ops.filter(lambda m: isinstance(m, PropertyChangedMessage) and m.sender is vm),
    ).subscribe(_on_msg)
    return sub.dispose

# Usage:
root = tk.Tk()
title_var = tk.StringVar()
save_command = RelayCommand.builder().task(save_note).build()
tk.Entry(root, textvariable=title_var).pack()
tk.Button(root, text="Save",
          command=lambda: save_command.execute(None)).pack()
dispose = bind_string(title_var, vm, hub)
root.protocol("WM_DELETE_WINDOW", lambda: (dispose(), root.destroy()))
root.mainloop()

9.7.4. Fuller example

examples/python/tk/todo_app/ — a working Tkinter Todo app backed by a CompositeVM[TodoItemVM].