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How do I Create an instance of a class in another class in Python

Answer 1

+1 A:

I don't know wxWidgets, but based on what I know of Python, I'm guessing that you need to change:

self.Bind(wx.EVT_MENU, self.subPanel(None, -1, 'TEST'),id=1)

to:

self.Bind(wx.EVT_MENU, subPanel(None, -1, 'TEST'),id=1)

"subPanel" is a globally defined class, not a member of "self" (which is a mainPanel).

Edit: Ah, "Bind" seems to bind an action to a function, so you need to give it a function that creates the other class. Try the following. It still doesn't work, but at least it now crashes during the subPanel creation.

self.Bind(wx.EVT_MENU, lambda(x): subPanel(None, -1, 'TEST'),id=1)

Glomek 2008-11-07 23:34:25

Answer 2

A:

Thanks for the answer but I think I tried that and it didn't work either. I am writing this in notepad and batch submitting it so I don't see why it crashed

2008-11-08 00:01:27

Answer 3

+1 A:

You should handle the button click event, and create the panel in your button handler (like you already do with your OnQuit method).

I think the following code basically does what you're after -- creates a new Frame when the button is clicked/menu item is selected.

import wx

class MyFrame(wx.Frame):
    def __init__(self, parent, title="My Frame", num=1):

        self.num = num
        wx.Frame.__init__(self, parent, -1, title)
        panel = wx.Panel(self)

        button = wx.Button(panel, -1, "New Panel")
        button.SetPosition((15, 15))
        self.Bind(wx.EVT_BUTTON, self.OnNewPanel, button)
        self.Bind(wx.EVT_CLOSE, self.OnCloseWindow)

        # Now create a menu
        menubar = wx.MenuBar()
        self.SetMenuBar(menubar)

        # Panel menu
        panel_menu = wx.Menu()

        # The menu item
        menu_newpanel = wx.MenuItem(panel_menu,
                                    wx.NewId(),
                                    "&New Panel",
                                    "Creates a new panel",
                                    wx.ITEM_NORMAL)
        panel_menu.AppendItem(menu_newpanel)

        menubar.Append(panel_menu, "&Panels")
        # Bind the menu event
        self.Bind(wx.EVT_MENU, self.OnNewPanel, menu_newpanel)

    def OnNewPanel(self, event):
        panel = MyFrame(self, "Panel %s" % self.num, self.num+1)
        panel.Show()

    def OnCloseWindow(self, event):
        self.Destroy()

def main():
    application = wx.PySimpleApp()
    frame = MyFrame(None)
    frame.Show()
    application.MainLoop()

if __name__ == "__main__":
    main()

Edit: Added code to do this from a menu.

Ryan Ginstrom 2008-11-08 01:10:57

Answer 4

A:

You need an event handler in your bind expression

self.bind(wx.EVT_MENU, subPanel(None, -1, 'TEST'),id=1)

needs to be changed to:

self.bind(wx.EVT_MENU, <event handler>, <id of menu item>)

where your event handler responds to the event and instantiates the subpanel:

def OnMenuItem(self, evt): #don't forget the evt
    sp = SubPanel(self, wx.ID_ANY, 'TEST')
    #I assume you will add it to a sizer
    #if you aren't... you should
    test_sizer.Add(sp, 1, wx.EXPAND)
    #force the frame to refresh the sizers:
    self.Layout()

Alternatively, you can instantiate the subpanel in your frame's __init__ and call a subpanel.Hide() after instantiation, and then your menuitem event handler and call a show on the panel subpanel.Show()

Edit: Here is some code that will do what I think that you are asking:

#!usr/bin/env python

import wx

class TestFrame(wx.Frame):
    def __init__(self, parent, *args, **kwargs):
        wx.Frame.__init__(self, parent, *args, **kwargs)
        framesizer = wx.BoxSizer(wx.VERTICAL)
        mainpanel = MainPanel(self, wx.ID_ANY)
        self.subpanel = SubPanel(self, wx.ID_ANY)
        self.subpanel.Hide()
        framesizer.Add(mainpanel, 1, wx.EXPAND)
        framesizer.Add(self.subpanel, 1, wx.EXPAND)
        self.SetSizerAndFit(framesizer)

class MainPanel(wx.Panel):
    def __init__(self, parent, *args, **kwargs):
        wx.Panel.__init__(self, parent, *args, **kwargs)
        panelsizer = wx.BoxSizer(wx.VERTICAL)
        but = wx.Button(self, wx.ID_ANY, "Add")
        self.Bind(wx.EVT_BUTTON, self.OnAdd, but)
        self.panel_shown = False
        panelsizer.Add(but, 0)
        self.SetSizer(panelsizer)

    def OnAdd(self, evt):
        if not self.panel_shown:
            self.GetParent().subpanel.Show()
            self.GetParent().Fit()
            self.GetParent().Layout()
            self.panel_shown = True
        else:
            self.GetParent().subpanel.Hide()
            self.GetParent().Fit()
            self.GetParent().Layout()
            self.panel_shown = False

class SubPanel(wx.Panel):
    def __init__(self, parent, *args, **kwargs):
        wx.Panel.__init__(self, parent, *args, **kwargs)
        spsizer = wx.BoxSizer(wx.VERTICAL)
        text = wx.StaticText(self, wx.ID_ANY, label='I am a subpanel')
        spsizer.Add(text, 1, wx.EXPAND)
        self.SetSizer(spsizer)

if __name__ == '__main__':
    app = wx.App()
    frame = TestFrame(None, wx.ID_ANY, "Test Frame")
    frame.Show()
    app.MainLoop()

DrBloodmoney 2008-11-08 01:19:19

Answer 5

A:

I appreciate these answers so far. I need to study Dr Bloodmoney's answer more carefully because I think he is getting me closest to what I am trying to do. I just have to figure out how to make it work in my code.

OkayThanks Dr. Bloodmoney-it worked. I had to tinker with the code some I am going to ask a new questions about the tinkering I had to do.

PyNEwbie 2008-11-08 03:16:37

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answers:

How do I Create an instance of a class in another class in Python

this is where I think I am being clever by using a button click to create an instance

of subPanel.

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