How to access a variable from one tab in another tab of a notebook?

[Mohsen Owzar]

Alan Gauld schrieb am Donnerstag, 8. April 2021 um 15:40:19 UTC+2:
> On 08/04/2021 06:01, Mohsen Owzar wrote: 
> 
> >> But this is why GUIs are often(usually?) built as a class 
> >> because you can store all the state variables within 
> >> the instance and access them from all the methods. 
> >> 
> >> You can do it with functions but you usually wind up 
> >> with way too many globals to be comfortable.
> > Because I'm a newbie in Python and write programs since 
> > a couple of months, and I'm not so familiar with classes,
> OK, In that case you should probably read up on classes 
> and play around with them to get used to the ideas of 
> classes, objects and methods. 
> 
> You can carry on using functions but you will need to 
> keep track of quite a lot of global variables which 
> can get messy in bigger programs. Classes just keep 
> things a bit more tidy.
> > would be very nice to give me a code, how I have to 
> > change my code into a class form. 
> > I tried without a class and I ran into problems that 
> > the defined frame and entry are not defined.
> One of the problems in your code is that you are not 
> storing references to the widgets you create. You are 
> relying on the containment tree to store the references 
> and keep them alive. But that makes it difficult to 
> access. As a general rule of thumb if you are creating 
> any widget that responds to events you should keep 
> a reference to it - ie. create a variable. 
> 
> For example in your code you have a section like this: 
> 
> def gen_t2(frame): 
> def getValue(event):...
> lbl = Label(frame, text='Val').pack() 
> 
> ent = Entry(frame) 
> ent.pack() 
> ent.insert(0, '2') 
> 
> ent.bind('<Return>', getValue)
> And you call it like this: 
> 
> if firstTime2 == 1: if firstTime2 == 1: 
> gen_t2(tab2) 
> firstTime2 = 0 
> 
> gen_t2(tab2) 
> firstTime2 = 0 
> 
> Inside the function you store a reference to the Entry as ent. 
> but ent disappears as soon as the function ends, you cannot 
> use ent to access your entry outside the function. 
> You need to return the widget like so: 
> 
> def gen_t2(frame): 
> def getValue(event):... 
> 
> ... 
> ent.bind('<Return>', getValue) 
> return ent 
> 
> And then call it like: 
> 
> if firstTime2: 
> entry_field = gen_t2(tab2) 
> firstTime2 = False 
> 
> Now you can access your Entry field via the global 
> variable entry_field. 
> 
> I suspect you should forget about the classes for now, focus 
> on getting the functions to work, especially returning values 
> and storing those in global variables that you can access from 
> elsewhere. These principles are just as important when you 
> get round to studying classes later. 
> 
> And remember that global variables in one module can be 
> accessed from another module by importing the first module 
> into the second and using the module name as prefix. 
> 
> import tab2 
> 
> txt = tab2.entry_field.get() 
> 
> HTH 
> 
> You might also find the functions, namespaces and GUI sections 
> of my tutorial useful (see below).
> -- 
> Alan G 
> Author of the Learn to Program web site 
> http://www.alan-g.me.uk/ 
> http://www.amazon.com/author/alan_gauld 
> Follow my photo-blog on Flickr at: 
> http://www.flickr.com/photos/alangauldphotos

Hello Alan,
I'm so happy that you have so good explained to me, what I have to do.
Now, it is a bit clearer how I can use the variables or references in another modules.
I try to follow your suggestions to see if I can solve my problem.
Again thank you very much.
Best regards
Mohsen