How can I change an attribute on the object when the attribute is Frame? I want to change the color of the frame.
class MyFrame:
def __init__(self, bg_color)
self.window = tk.Frame(self.parent, bg=bg_color)
mainApp:
frame_obj = MyFrame("blue")
#want to change the color after the frame obj has been created
frame_obj.window.bg = "red" #this does not work
Tkinter is based on different progamming language, named tcl and thats why things seem a bit unpythonic here.
The tk.Frame object isnt a pure python object, rather its an wrapped object in a tcl interpreter and thats why you cant address the attributes you intuitivly think you can. You need to adress the attributes in a way the tcl interpreter is abel to handle and therefor methods are created like widget.configure.
To achive what you want with your current code, it would look like:
import tkinter as tk
root = tk.Tk()
class MyFrame():
def __init__(self, bg_color):
self.window = tk.Frame(width=500,height=500,bg=bg_color)
frame_obj = MyFrame('blue')
frame_obj.window.pack(fill=tk.BOTH)
frame_obj.window.configure(bg='yellow')
root.mainloop()
In addition, the proper way for an OOP approach for a frame would look like this:
class MyFrame(tk.Frame):
def __init__(self,master,**kwargs):
super().__init__(master)
self.configure(**kwargs)
frame_obj = MyFrame(root,width=500,height=500,bg='green')
frame_obj.pack(fill=tk.BOTH)
This way your class becomes a child of the tk.Frame object and you can adress it directly. The syntax self in this context refers directly to the tk.Frame object. Also it is good practice to use the format of
def __init__(self,master,**kwargs):
while its the same for the parent/tk.Frame. It has a single positional argument, named master and keywords arguments for the configuration of the Frame.
Please take a look at a tutorial for tkinter and for OOP. If you had you would know that. Please dont feel offended, but StackOverflow requiers a brief reasearch and that includes to read documentation and take tutorials.
I have a big problem using tkinter with self here is my code
Could people please give an answer, thanks! The error I get is something like,self could not be given a variable outside a function.
from tkinter import *
root = Tk()
class start():
global self
self = root
def __init__():
self.title('__init__')
self.geometry('300x300')
__init__(self)
class window_extra():
def canvas(self):
global self
selfc = Canvas(self, bg='black').pack()
canvas(self)
self.mainloop()
Thanks!
You should not use self as a variable name as it is used to specify if something is an attribute of the instance of the class.
You do not need to use global in classes either as class attributes are used in most cases when dealing with variables that are needed through the class.
Judging by the code you have shown I think you are trying to do something like this:
from tkinter import *
class start():
def __init__(self, root):
self.master = root
self.master.title('__init__')
self.master.geometry('300x300')
Canvas(self.master, bg='black').pack()
root = Tk()
start(root)
root.mainloop()
However I believe you are struggling with the OOP method of programing and I would suggest to not use OOP to start with if this is the case.
Maybe take a few tutorials on youtube or hit up Codecadamy.
In response to your comments:
In my Opinion using init properly is a bad idea. I use it as a regular def. I doesn't matter if I use self global, unless the function/class variable is called self.
I respect the proper use of init, but I just find the whole thing with, init and self.master I just don't get any of it!
Lack of understanding a thing does not mean said thing is bad. The use of self.master is there to provide a class attribute that ties back to the root Tk() variable. This allows any method within the class to interact with the instance of Tk(). I can't speak to other programing languages but the use of self is a very important in OOP for python. It may not be 100% required to reserve self for referencing to either the instance of the object or the class attribute but it is the accepted and known use of self and really should not be changed/overwritten.
I restructured for some simplicity, but I think that you need a better understanding of objects in Python before going too much further down the GUI route. I think that you mean something like this:
from tkinter import *
# creates a subclass of Tk() called 'Application'; class names by convention
# use CamelCase; best to stick with convention on this one
class Application(tkinter.Tk):
# you don't have to create an explicit invocation of '__init__', it
# is automatically run when you instantiate your class (last line)
def __init__():
super().__init__() # initialize the super class (the 'tkinter.Tk()')
self.title('__init__') # use 'self' to refer to this object - do not declare it as global! it is only valid within the object!
self.geometry('300x300')
self.my_canvas = tkinter.Canvas(self, bg='black') # save an instance of your canvas for easy reference later
self.my_canvas.pack() # pack as a separate step (only required if you plan to use the canvas later... or ever)
self.mainloop() # begin the tkinter loop
# this 'if __name__ ...' is a good idea in most cases, allows you to import `Application` into other
# files without actually running it unless you want to from that other file
if __name__ == '__main__':
Application() # start your class
Am having much trouble splitting PyQt code:
main.py
(PyQt modules)
from titles import *
appl = QApplication(sys.argv)
from main import Ui_MainWindow
class Main(QMainWindow):
def __init__(self, parent=None):
super(Main, self).__init__(parent)
QMainWindow.__init__(self)
self.u = Ui_MainWindow()
self.u.setupUi(self)
Titles(self)
titles.py
import sys
(PyQt modules)
(dbconnections)
class Titles():
def __init__(self, a): #<-- APP IS PASSED AS ARGUMENT AND NOW CALLED 'A'
a.u.table.setModel(titles)
a.u.lineEdit.setText("Titles Init")
a.u.add.clicked.connect(titles.insertRow)
class TitlesTableModel(QSqlTableModel):
def __init__(self):
QSqlTableModel.__init__(self)
self.setTable("titles")
self.setEditStrategy(self.OnFieldChange)
self.select()
def insertRow(self):
return self.insertRecord(-1, self.record())
a.u.lineEdit.setText("Insert Title")
titles = Titles()
Running main.py loads all data. QPushButton inserts a row, but doesn't set lineEdit to "Insert Title", because "a" isn't defined globally. Mostly tried creating a function in titles.py, triggered when main.py loads, looking like:
a = 0 #<-- THIS WAS A LAST STRAW AS WARNED BY RESEARCHING OTHERS, BUT AM LOST
def start(app):
global a
a = app
Titles(a); TitlesTableModel(a) #<-- EVEN THOUGH TITLES.PY IS IMPORTED, IT DIDN'T INCLUDE THE APP REFERENCE, SO AM TRYING TO 'REFRESH' THE TITLESTABLEMODEL
...with Titles & TitlesTableModel requiring an extra argument (self, a)
This loads data & functions, but again, insertRow doesn't update lineEdit.
Other attempt
change Songs class to
class Songs():
def __init__(self, a):
titles = Titles(a)
...(rest the same)
...and removing titles=Titles() from below the model definition. This again, shows data, but doesn't update lineEdit when pressing 'Add'.
Ultimately, it feels titles.py needs to have 'from main import *', but the main applications instance is defined after titles.py is called, and importing main.Main creates a recursion. Have tried inheriting multiple times via 'from main import Main', & writing 'class Songs(Main)' (so Songs can use the UI without passing a reference), but again, recursion occurs. Nine hours today plus three weeks prior looking at others, so am really stumped. Others somewhat recommended using a config file of even 'builtin', but that looks very bad.
Regards
In PyQt, classes generally use Signals to communicate between one another, especially when one class inherits from QWidget and the other does not inherit from that, as you've demonstrated by connecting signals (albeit wrongly, or at least you're missing bits and pieces of your code here on SO).
However, your insertRow() -> lineEdit method as it stands will never be called because it follows a return statement, meaning that the lineEdit part will never be hit. But I would be surprised if this fixed the problem.
Also, I would consider redesigning (refactoring) your code from the grounds up. Is there really a reason you have a different Titles() class?
While this is shameless self-promotion, I think you might benefit from my course on YouTube that deals with building Python applications using PySide (which is nearly identical to PyQt) - I discuss cross-thread (cross-class) communication a fair bit - link is http://youtube.com/Deusdies2
Your code has several issues, but the main problem is the snippet:
def insertRow(self):
return self.insertRecord(-1, self.record())
a.u.lineEdit.setText("Insert Title")
as you can see you're returning from the function before the line a.u.lineEdit.setText("Insert Title") get excecuted. Hence, this function willl never change the text of your QLineEdit.
Change your code b
def insertRow(self):
a.u.lineEdit.setText("Insert Title") # First change text.
return self.insertRecord(-1, self.record()) # Then insert record and return.
On the other hand: If you are working with global variables (a bad practice, I have to say) why are you passing it as arguments? Try to not use global variables at least is absolutly necesary.
I have been playing with the Ruby library "shoes". Basically you can write a GUI application in the following way:
Shoes.app do
t = para "Not clicked!"
button "The Label" do
alert "You clicked the button!" # when clicked, make an alert
t.replace "Clicked!" # ..and replace the label's text
end
end
This made me think - how would I design a similarly nice-to-use GUI framework in Python? One that doesn't have the usual tyings of basically being wrappers to a C* library (In the case of GTK, Tk, wx, QT etc etc)
Shoes takes things from web devlopment (like #f0c2f0 style colour notation, CSS layout techniques, like :margin => 10), and from ruby (extensively using blocks in sensible ways)
Python's lack of "rubyish blocks" makes a (metaphorically)-direct port impossible:
def Shoeless(Shoes.app):
self.t = para("Not clicked!")
def on_click_func(self):
alert("You clicked the button!")
self.t.replace("clicked!")
b = button("The label", click=self.on_click_func)
No where near as clean, and wouldn't be nearly as flexible, and I'm not even sure if it would be implementable.
Using decorators seems like an interesting way to map blocks of code to a specific action:
class BaseControl:
def __init__(self):
self.func = None
def clicked(self, func):
self.func = func
def __call__(self):
if self.func is not None:
self.func()
class Button(BaseControl):
pass
class Label(BaseControl):
pass
# The actual applications code (that the end-user would write)
class MyApp:
ok = Button()
la = Label()
#ok.clicked
def clickeryHappened():
print "OK Clicked!"
if __name__ == '__main__':
a = MyApp()
a.ok() # trigger the clicked action
Basically the decorator function stores the function, then when the action occurred (say, a click) the appropriate function would be executed.
The scope of various stuff (say, the la label in the above example) could be rather complicated, but it seems doable in a fairly neat manner..
You could actually pull this off, but it would require using metaclasses, which are deep magic (there be dragons). If you want an intro to metaclasses, there's a series of articles from IBM which manage to introduce the ideas without melting your brain.
The source code from an ORM like SQLObject might help, too, since it uses this same kind of declarative syntax.
I was never satisfied with David Mertz's articles at IBM on metaclsses so I recently wrote my own metaclass article. Enjoy.
This is extremely contrived and not pythonic at all, but here's my attempt at a semi-literal translation using the new "with" statement.
with Shoes():
t = Para("Not clicked!")
with Button("The Label"):
Alert("You clicked the button!")
t.replace("Clicked!")
The hardest part is dealing with the fact that python will not give us anonymous functions with more than one statement in them. To get around that, we could create a list of commands and run through those...
Anyway, here's the backend code I ran this with:
context = None
class Nestable(object):
def __init__(self,caption=None):
self.caption = caption
self.things = []
global context
if context:
context.add(self)
def __enter__(self):
global context
self.parent = context
context = self
def __exit__(self, type, value, traceback):
global context
context = self.parent
def add(self,thing):
self.things.append(thing)
print "Adding a %s to %s" % (thing,self)
def __str__(self):
return "%s(%s)" % (self.__class__.__name__, self.caption)
class Shoes(Nestable):
pass
class Button(Nestable):
pass
class Alert(Nestable):
pass
class Para(Nestable):
def replace(self,caption):
Command(self,"replace",caption)
class Command(Nestable):
def __init__(self, target, command, caption):
self.command = command
self.target = target
Nestable.__init__(self,caption)
def __str__(self):
return "Command(%s text of %s with \"%s\")" % (self.command, self.target, self.caption)
def execute(self):
self.target.caption = self.caption
## All you need is this class:
class MainWindow(Window):
my_button = Button('Click Me')
my_paragraph = Text('This is the text you wish to place')
my_alert = AlertBox('What what what!!!')
#my_button.clicked
def my_button_clicked(self, button, event):
self.my_paragraph.text.append('And now you clicked on it, the button that is.')
#my_paragraph.text.changed
def my_paragraph_text_changed(self, text, event):
self.button.text = 'No more clicks!'
#my_button.text.changed
def my_button_text_changed(self, text, event):
self.my_alert.show()
## The Style class is automatically gnerated by the framework
## but you can override it by defining it in the class:
##
## class MainWindow(Window):
## class Style:
## my_blah = {'style-info': 'value'}
##
## or like you see below:
class Style:
my_button = {
'background-color': '#ccc',
'font-size': '14px'}
my_paragraph = {
'background-color': '#fff',
'color': '#000',
'font-size': '14px',
'border': '1px solid black',
'border-radius': '3px'}
MainWindow.Style = Style
## The layout class is automatically generated
## by the framework but you can override it by defining it
## in the class, same as the Style class above, or by
## defining it like this:
class MainLayout(Layout):
def __init__(self, style):
# It takes the custom or automatically generated style class upon instantiation
style.window.pack(HBox().pack(style.my_paragraph, style.my_button))
MainWindow.Layout = MainLayout
if __name__ == '__main__':
run(App(main=MainWindow))
It would be relatively easy to do in python with a bit of that metaclass python magic know how. Which I have. And a knowledge of PyGTK. Which I also have. Gets ideas?
With some Metaclass magic to keep the ordering I have the following working. I'm not sure how pythonic it is but it is good fun for creating simple things.
class w(Wndw):
title='Hello World'
class txt(Txt): # either a new class
text='Insert name here'
lbl=Lbl(text='Hello') # or an instance
class greet(Bbt):
text='Greet'
def click(self): #on_click method
self.frame.lbl.text='Hello %s.'%self.frame.txt.text
app=w()
The only attempt to do this that I know of is Hans Nowak's Wax (which is unfortunately dead).
The closest you can get to rubyish blocks is the with statement from pep343:
http://www.python.org/dev/peps/pep-0343/
If you use PyGTK with glade and this glade wrapper, then PyGTK actually becomes somewhat pythonic. A little at least.
Basically, you create the GUI layout in Glade. You also specify event callbacks in glade. Then you write a class for your window like this:
class MyWindow(GladeWrapper):
GladeWrapper.__init__(self, "my_glade_file.xml", "mainWindow")
self.GtkWindow.show()
def button_click_event (self, *args):
self.button1.set_label("CLICKED")
Here, I'm assuming that I have a GTK Button somewhere called button1 and that I specified button_click_event as the clicked callback. The glade wrapper takes a lot of effort out of event mapping.
If I were to design a Pythonic GUI library, I would support something similar, to aid rapid development. The only difference is that I would ensure that the widgets have a more pythonic interface too. The current PyGTK classes seem very C to me, except that I use foo.bar(...) instead of bar(foo, ...) though I'm not sure exactly what I'd do differently. Probably allow for a Django models style declarative means of specifying widgets and events in code and allowing you to access data though iterators (where it makes sense, eg widget lists perhaps), though I haven't really thought about it.
Maybe not as slick as the Ruby version, but how about something like this:
from Boots import App, Para, Button, alert
def Shoeless(App):
t = Para(text = 'Not Clicked')
b = Button(label = 'The label')
def on_b_clicked(self):
alert('You clicked the button!')
self.t.text = 'Clicked!'
Like Justin said, to implement this you would need to use a custom metaclass on class App, and a bunch of properties on Para and Button. This actually wouldn't be too hard.
The problem you run into next is: how do you keep track of the order that things appear in the class definition? In Python 2.x, there is no way to know if t should be above b or the other way around, since you receive the contents of the class definition as a python dict.
However, in Python 3.0 metaclasses are being changed in a couple of (minor) ways. One of them is the __prepare__ method, which allows you to supply your own custom dictionary-like object to be used instead -- this means you'll be able to track the order in which items are defined, and position them accordingly in the window.
This could be an oversimplification, i don't think it would be a good idea to try to make a general purpose ui library this way. On the other hand you could use this approach (metaclasses and friends) to simplify the definition of certain classes of user interfaces for an existing ui library and depending of the application that could actually save you a significant amount of time and code lines.
I have this same problem. I wan to to create a wrapper around any GUI toolkit for Python that is easy to use, and inspired by Shoes, but needs to be a OOP approach (against ruby blocks).
More information in: http://wiki.alcidesfonseca.com/blog/python-universal-gui-revisited
Anyone's welcome to join the project.
If you really want to code UI, you could try to get something similar to django's ORM; sth like this to get a simple help browser:
class MyWindow(Window):
class VBox:
entry = Entry()
bigtext = TextView()
def on_entry_accepted(text):
bigtext.value = eval(text).__doc__
The idea would be to interpret some containers (like windows) as simple classes, some containers (like tables, v/hboxes) recognized by object names, and simple widgets as objects.
I dont think one would have to name all containers inside a window, so some shortcuts (like old-style classes being recognized as widgets by names) would be desirable.
About the order of elements: in MyWindow above you don't have to track this (window is conceptually a one-slot container). In other containers you can try to keep track of the order assuming that each widget constructor have access to some global widget list. This is how it is done in django (AFAIK).
Few hacks here, few tweaks there... There are still few things to think of, but I believe it is possible... and usable, as long as you don't build complicated UIs.
However I am pretty happy with PyGTK+Glade. UI is just kind of data for me and it should be treated as data. There's just too much parameters to tweak (like spacing in different places) and it is better to manage that using a GUI tool. Therefore I build my UI in glade, save as xml and parse using gtk.glade.XML().
Personally, I would try to implement JQuery like API in a GUI framework.
class MyWindow(Window):
contents = (
para('Hello World!'),
button('Click Me', id='ok'),
para('Epilog'),
)
def __init__(self):
self['#ok'].click(self.message)
self['para'].hover(self.blend_in, self.blend_out)
def message(self):
print 'You clicked!'
def blend_in(self, object):
object.background = '#333333'
def blend_out(self, object):
object.background = 'WindowBackground'
Here's an approach that goes about GUI definitions a bit differently using class-based meta-programming rather than inheritance.
This is largley Django/SQLAlchemy inspired in that it is heavily based on meta-programming and separates your GUI code from your "code code". I also think it should make heavy use of layout managers like Java does because when you're dropping code, no one wants to constantly tweak pixel alignment. I also think it would be cool if we could have CSS-like properties.
Here is a rough brainstormed example that will show a column with a label on top, then a text box, then a button to click on the bottom which shows a message.
from happygui.controls import *
MAIN_WINDOW = Window(width="500px", height="350px",
my_layout=ColumnLayout(padding="10px",
my_label=Label(text="What's your name kiddo?", bold=True, align="center"),
my_edit=EditBox(placeholder=""),
my_btn=Button(text="CLICK ME!", on_click=Handler('module.file.btn_clicked')),
),
)
MAIN_WINDOW.show()
def btn_clicked(sender): # could easily be in a handlers.py file
name = MAIN_WINDOW.my_layout.my_edit.text
# same thing: name = sender.parent.my_edit.text
# best practice, immune to structure change: MAIN_WINDOW.find('my_edit').text
MessageBox("Your name is '%s'" % ()).show(modal=True)
One cool thing to notice is the way you can reference the input of my_edit by saying MAIN_WINDOW.my_layout.my_edit.text. In the declaration for the window, I think it's important to be able to arbitrarily name controls in the function kwargs.
Here is the same app only using absolute positioning (the controls will appear in different places because we're not using a fancy layout manager):
from happygui.controls import *
MAIN_WINDOW = Window(width="500px", height="350px",
my_label=Label(text="What's your name kiddo?", bold=True, align="center", x="10px", y="10px", width="300px", height="100px"),
my_edit=EditBox(placeholder="", x="10px", y="110px", width="300px", height="100px"),
my_btn=Button(text="CLICK ME!", on_click=Handler('module.file.btn_clicked'), x="10px", y="210px", width="300px", height="100px"),
)
MAIN_WINDOW.show()
def btn_clicked(sender): # could easily be in a handlers.py file
name = MAIN_WINDOW.my_edit.text
# same thing: name = sender.parent.my_edit.text
# best practice, immune to structure change: MAIN_WINDOW.find('my_edit').text
MessageBox("Your name is '%s'" % ()).show(modal=True)
I'm not entirely sure yet if this is a super great approach, but I definitely think it's on the right path. I don't have time to explore this idea more, but if someone took this up as a project, I would love them.
Declarative is not necessarily more (or less) pythonic than functional IMHO. I think a layered approach would be the best (from buttom up):
A native layer that accepts and returns python data types.
A functional dynamic layer.
One or more declarative/object-oriented layers.
Similar to Elixir + SQLAlchemy.