Python 2.7 : Tkinter, How to use the bind method?

Question

I'm trying to create a Scrabble game with Python. I'd like to display the points that the word worth when the user is typing the word. I already asked this question as I didn't know what method to use. As I discovered which method to use, and my question is about how to use this method, I think this deserve a new question. My problem is that I created a function called bind_entry(event) that is supposed to set a label every time the user type a letter. But the function bind_entry(event)doesn't know the label to set and the entry where the word is.

Here is my code :

#this the function creating the label
def create_variabletext_intlabel(root,col,row):
    val=IntVar()
    label=Label(root,textvariable=val)
    label.grid(column=col,row=row)
    return val, label

#this is the function creating the entry
def create_entry_string(root,width,col,row,columnspan,rowspan):
    val=StringVar()
    entry=ttk.Entry(root,width=width,textvariable=val)
    entry.grid(column=col,row=row,columnspan=columnspan,rowspan=rowspan)
    entry.bind("<Any-KeyPress>",bind_entry)
    #Here is my problem, when I call the function bind_entry.
    return val, entry

def bind_entry(event):
    label.set(m.counting_point(char(event))) 
    # m.counting_point() is a function counting the word's points
    # my problem is that the function doesn't know yet the label. 
    # I don't know how to call the label. 

# I call the function create_entry_string in another file initiating
# all the widget for the GUI
val_entry_word, entry_word =g.create_entry_string(root,15,1,1,1,1)

# I call the function create_variabletext_intlabel in another file
# initiating all the widget for the GUI
val_points,label_points=g.create_variabletext_intlabel(root,1,2)

I just noticed that the function m.counting_points() will count only the letter that is typed by the user. Here I should call val_entry_word.

So here is my question :

As val_entry_word and val_points are created in a function in another file How could I call val_entry_word and val_points in the function bind_entry() ?

Answer 1

Generally, when you need different function calls to share information without passing it explicitly, the best practice is to use a class.

e.g.

class LabelUpdater(object):
    def create_variabletext_intlabel(self,root,col,row):
        val=IntVar()
        self.label=label=Label(root,textvariable=val)
        label.grid(column=col,row=row)
        return val, label

    #this is the function creating the entry
    def create_entry_string(self,root,width,col,row,columnspan,rowspan):
        val=StringVar()
        entry=ttk.Entry(root,width=width,textvariable=val)
        entry.grid(column=col,row=row,columnspan=columnspan,rowspan=rowspan)
        entry.bind("<Any-KeyPress>",self.bind_entry)
        #Here is my problem, when I call the function bind_entry.
        return val, entry

     def bind_entry(self,event):
        self.label.set(m.counting_point(char(event))) 

#At this point, I don't understand your code anymore since I don't know what g
#is or how it's create_entry_string method calls your create_entry_string function...
#I'll assume that the module where g's class is defined imports this file...
#If that's how it works, then the following may be ok, although probably not because
#of circular imports...

container=LabelUpdater()
create_variabletext_intlabel=container.create_variabletext_intlabel
create_entry_string=container.create_entry_string

val_entry_word, entry_word =g.create_entry_string(root,15,1,1,1,1) #somehow calls create_variabletext_intlabel which is mapped to container.create_variable_intlabel???

# I call the function create_variabletext_intlabel in another file
# initiating all the widget for the GUI
val_points,label_points=g.create_variabletext_intlabel(root,1,2)

Of course, you could also use globals...(though that is definitely discouraged)

Finally, an idiom that I often use to add additional information in a bind callback is to wrap the callback function in another function...

def myfunc(root):
    label=Label(root,text="cow")
    label.pack()
    return label

#This is the callback we want...
#  Q: but how do we pass S? 
#  A: we need to wrap this call in another -- a perfect use for lambda functions!
def change_label(label,S):
    label.config(text=S)

root=Tk()
lbl=myfunc(root)
lbl.bind("<Enter>",lambda e: change_label("Horse"))
lbl.bind("<Leave>",lambda e: change_label("Cow"))