pythonwxpythonpartial-functionspypubsub

WxPython PyPubSub, using curried function not working


I'm using the PyPubSub module of WxPython, to send messages around, and I want to have a function subscribed to a topic, where the function has some curried parameters. Unfortunately, it doesn't seem to be using the curried function as I would expect.

from functools import partial
import time

import wx
from pubsub import pub

def MakeStatusBar(top_frame):

    statusbar = top_frame.CreateStatusBar()
    statusbar.SetFieldsCount(2)
    statusbar.SetStatusWidths([400, 400])

    # pub.subscribe(listener=got_msg, topicName='game.new')  # Works, when alone

    status_func = partial(got_status_msg, statusbar)
    print(f"status_func[callable={callable(status_func)}] = {status_func}")
    status_func(some_data='Directly calling the curried-function')  # Calling the function directly - works
    pub.subscribe(listener=status_func, topicName='game.new')  # Breaks

    return statusbar

def got_msg(some_data):
    print(f"\n*** got_msg: data = {some_data}\n")

def got_status_msg(status_bar, some_data):
    print(f"\n*** got_status_msg, args = {some_data}\n")
    status_bar.SetStatusText(some_data, 0)

class topFrame(wx.Frame):
    def __init__(self, parent):
        super().__init__(parent, wx.ID_ANY, title='testing', size=(500, 500))
        self.status_bar = (MakeStatusBar(self))

class myApp(wx.App):
    def __init__(self):
        wx.App.__init__(self, redirect=True, filename='errlog.txt')  # To log error to a file
        # super().__init__(self)  # Doesn't take redirect? Weird.

        self.topFrame = topFrame(None)
        self.SetTopWindow(self.topFrame)
        self.topFrame.Show()
        print(f"in 2 seconds, will send a message to the Statusbar")
        time.sleep(2)
        print(f"sending...\n")

        try:
            pub.sendMessage(topicName='game.new', some_data='publishing a new-game message')
        except Exception as ex:
            print(f"WTF? got {str(ex)}\n")
        print(f"message has been sent.\n")

if __name__ == '__main__':
    my_app = myApp()
    my_app.MainLoop()

The error that I get is:

Traceback (most recent call last):
  File "/Code/wxpy/hex_test/src/wx/menu_bar.py", line 11, in new_game_msg
    pub.sendMessage(topicName='game.new', some_data='this is a test message')
    raise SenderUnknownMsgDataError(self.topicNameTuple,
pubsub.core.topicargspec.SenderUnknownMsgDataError: 
Some optional args unknown in call to sendMessage('('game', 'new')', some_data): some_data

So how can I pass a listener-function to the topic, that has at least one parameter baked in? Obviously there's other ways of doing this (a global variable, for one), but I feel like this should be do-able with a partial function.


Solution

  • Well, after staring at it, and reading the docs more, yes, there is a solution. It's already baked into PyPubSub, where the listener itself already allows for curried arguments. I can just directly pass in the StatusBar parameter I want.

        # status_func = partial(got_status_msg, statusbar)
        # print(f"status_func[callable={callable(status_func)}] = {status_func}")
        # status_func(some_data='Directly calling the curried-function')  # Calling the function directly - works
    
        pub.subscribe(listener=got_status_msg, topicName='game.new', status_bar=statusbar)  # Now works
    

    So apparently the developers of PyPubSub anticipated this use. Good work. :)