OOP Concept

[Stefano Mtangoo]

Hello All,
Greetings!
I have question concerning OOP with Python. I want to know when Python class or being specific, how py class ends in package like wxpython.

What I mean is I have one class let say of frame and another class of a dialog box all in same py file. When Frame runs, uses self i.e self.button = wx.Button. This object belongs to frame. And let say we have text control in the other class (dialog). How do I call method of another class from the other class, i.e how do I call button from dialog and dialog from button.

Suppose I want to manipulate the button, let say its label, but from another class which it doesn't belong (In this case Dialog)?

I hhave done these without grasp thge real concept. I have dug up but I find difficult to grasp it wel; so, need your support!

[Ene Uran]

Maybe this short example will help:

# reference across class instances
# from one panel class to another panel class

import wx
import time

class MyPanel1(wx.Panel):
    def __init__(self, parent):
        wx.Panel.__init__(self, parent, wx.ID_ANY,
            pos=(0,0), size=(300, 100))
        self.SetBackgroundColour("green")
        self.button = wx.Button(self, label=" panel1 button ")
        self.button.Bind(wx.EVT_BUTTON, self.buttonClick )

    def buttonClick(self, event):
        """
        use the panel2 label and
        reference via the parent --> frame
        """
        #  display something that indicates a change
        s = time.strftime("%H:%M:%S", time.localtime())
        frame.panel2.label.SetLabel(s)


class MyPanel2(wx.Panel):
    def __init__(self, parent):
        wx.Panel.__init__(self, parent, wx.ID_ANY,
            pos=(0, 100), size=(300, 100))
        self.SetBackgroundColour("yellow")
        self.label = wx.StaticText(self, wx.ID_ANY, " panel2 label ")


app = wx.App(0)
# create a frame, no parent, default ID, title, size
caption = "wx.Panel()"
frame = wx.Frame(None, wx.ID_ANY, caption, size=(300, 220))

# note that frame is the parent for the two panels
frame.panel1 = MyPanel1(frame)
frame.panel2 = MyPanel2(frame)

frame.Show(True)
app.MainLoop()

[vegaseat]

Ene, you are using global instances, so the frame.panel1 or frame.panel2 reference is actually not needed. You can just use panel1 and panel2. However, your approach keeps things together.

[Stefano Mtangoo]

hello Ene, Vega and All Daniweb,
Please assist me on how calling is done on this line:

frame.panel2.label.SetLabel(s)

Does it change the label of

self.label = wx.StaticText(self, wx.ID_ANY, " panel2 label ")

????

What are you really doing with this line of codes? Are you appending them to table??
I ask because I have never used before this such way of coding in py
[

frame.panel1 = MyPanel1(frame)
frame.panel2 = MyPanel2(frame)

Thanks for your answers

[vegaseat]

Yes, in Ene's code she references
self.label = wx.StaticText(self, wx.ID_ANY, " panel2 label ")
created in panel2 with
frame.panel2.label.SetLabel(s)
used in panel1

The trick here is to create the instances for both panels in __main__ to make them globally available.

If you don't want to use global instances, then you can let the parent carry the connection ...

# reference across class instances
# from one panel class to another panel class
# via common parent

import wx
import time

class MyFrame(wx.Frame):
    def __init__(self, parent, mytitle, mysize):
        wx.Frame.__init__(self, parent, wx.ID_ANY, mytitle, size=mysize)

        # here panel1 and panel2 are local
        # but can be accessed via the parent
        self.panel1 = MyPanel1(parent=self)
        self.panel2 = MyPanel2(parent=self)


class MyPanel1(wx.Panel):
    def __init__(self, parent):
        wx.Panel.__init__(self, parent, wx.ID_ANY,
            pos=(0,0), size=(300, 100))
        # parent is common to both panels and
        # in this case cross references the panels
        self.parent = parent
        self.SetBackgroundColour("green")
        self.button = wx.Button(self, label=" panel1 button ")
        self.button.Bind(wx.EVT_BUTTON, self.buttonClick )

    def buttonClick(self, event):
        """
        use the panel2 label and
        reference via the parent --> frame
        """
        #  display something that indicates a change
        s = time.strftime("%H:%M:%S", time.localtime())
        # parent, or in this case self.parent, allows you to
        # get to widgets created in panel2
        self.parent.panel2.label.SetLabel(s)


class MyPanel2(wx.Panel):
    def __init__(self, parent):
        wx.Panel.__init__(self, parent, wx.ID_ANY,
            pos=(0, 100), size=(300, 100))
        self.SetBackgroundColour("yellow")
        self.label = wx.StaticText(self, wx.ID_ANY, " panel2 label ")


app = wx.App(0)
# create a frame parent=None, title, size
mytitle = "cross reference via common parent"
MyFrame(None, mytitle, (300, 220)).Show(True)
app.MainLoop()

This is IMHO a little cleaner and safer. No offence Ene!

[Stefano Mtangoo]

code is self explanatory. However I have to be sure that I grasped the concept and then go for practice:

self.parent.panel2.label.SetLabel(s)

suppose I have two dialog boxes and both have parent called frm and dialogs dia1 and dia2
dia1 a button, and dia2 a button. The dialog1 appears automatically after some time (that is easy to do) and when you press the button it calls dialog2 and get destroyed. I need its theory and even veeery simple example and the rest is my exercise!

Sorry for bothering and thanks for response!
Steve

[sneekula]

At this point you better give us some code, or we all get lost.

[Stefano Mtangoo]

#call dialog, type new caption, set it to static text and destroy the dialog
import wx
class Main(wx.Frame):
	def __init__ (self, parent, id, title):
		wx.Frame.__init__(self, parent, id, title)
		panel = wx.Panel(self, -1)
		#Make button
		bu = wx.Button(panel, -1, "Call")
		self.Bind(wx.EVT_BUTTON, self.OnCall, id=bu.GetId())
		#create static text ctrl
		title = wx.StaticText(panel,-1, "Original Text", style=wx.ALIGN_LEFT)
		#Add to sizer
		sizer = wx.BoxSizer(wx.VERTICAL)
		sizer.Add(title, 1, wx.EXPAND |wx.ALL, 10)
		sizer.Add(bu, 0, wx.ALL, 10)
		panel.SetSizer(sizer)
		panel.Layout()
		
	def OnCall(self, event):
		dialog = Dialog(self, -1, "Change caption")
		dialog.Show(True)
		Main.Hide()
		
#Dialog box as another class
class Dialog(wx.Dialog):
	def __init__(self,  parent, id, title):
		wx.Dialog.__init__(self, parent, id, title)
		self.text = wx.TextCtrl(self, -1)
		ok = wx.Button(self, -1, "Ok")
		#Bind to event tochange caption of Title=text
		self.Bind(self, wx.EVT_BUTTON, self.OnChangeCaption, id = ok.GetId())
		sizer2 = wx.BoxSizer()
		sizer2.Add(self.text, 1, wx.EXPAND |wx.ALL, 10)
		sizer2.Add(ok, 0, wx.ALL, 10)
		self.SetSizer(sizer2)
		self.Layout()		
		
	def OnChangeCaption(self, event):
		newlabel = self.text.GetValue()
		self.title.SetLabel(newlabel)

app = wx.App(False)
f = Main(None, -1, "Call Children from parent")
f.Show(True)
app.MainLoop()

[vegaseat]

So what is your error?

[Stefano Mtangoo]

when i click call button I get:

Traceback (most recent call last):
File "C:\Users\Elijah Ministries\Documents\NetBeansProjects\Learning Python\src\database - Griboullis.py", line 20, in OnCall
dialog = Dialog(self, -1, "Change caption")
File "C:\Users\Elijah Ministries\Documents\NetBeansProjects\Learning Python\src\database - Griboullis.py", line 31, in __init__
self.Bind(self, wx.EVT_BUTTON, self.OnChangeCaption, id = ok.GetId())
File "C:\Python25\Lib\site-packages\wx-2.8-msw-unicode\wx\_core.py", line 3885, in Bind
id = source.GetId()
AttributeError: 'function' object has no attribute 'GetId'