StringVar,
IntVar, DoubleVar, and BooleanVar, as well as some common
methods for interacting with these variables.
Tkinter provides variable classes to manage widget values dynamically:
StringVar: For string variables.IntVar: For integer variables.DoubleVar: For floating-point variables.BooleanVar: For boolean variables.StringVarStringVar is used to manage text values in widgets such as Entry,
Label, etc.
Example:
import tkinter as tk
def update_label(*args):
label.config(text=entry_var.get())
# Create the main window
root = tk.Tk()
root.title("StringVar Example")
root.geometry("300x200")
# Create a StringVar
entry_var = tk.StringVar()
# Create an Entry widget
entry = tk.Entry(root, textvariable=entry_var)
entry.pack(pady=20)
# Create a Label widget
label = tk.Label(root, text="Type something above")
label.pack(pady=10)
# Trace the variable to update the label when entry changes
entry_var.trace_add("write", update_label)
# Run the application
root.mainloop()
entry_var = tk.StringVar(): Creates a StringVar instance.textvariable=entry_var: Links the StringVar to the Entry
widget.entry_var.trace_add("write", update_label): Traces changes to the variable and
calls the update_label function when the variable's value changes.IntVarIntVar is used to manage integer values in widgets such as Spinbox,
Scale, etc.
Example:
import tkinter as tk
def update_label(*args):
label.config(text=f"Value: {spinbox_var.get()}")
# Create the main window
root = tk.Tk()
root.title("IntVar Example")
root.geometry("300x200")
# Create an IntVar
spinbox_var = tk.IntVar()
# Create a Spinbox widget
spinbox = tk.Spinbox(root, from_=0, to=10, textvariable=spinbox_var)
spinbox.pack(pady=20)
# Create a Label widget
label = tk.Label(root, text="Value: 0")
label.pack(pady=10)
# Trace the variable to update the label when spinbox changes
spinbox_var.trace_add("write", update_label)
# Run the application
root.mainloop()
spinbox_var = tk.IntVar(): Creates an IntVar instance.textvariable=spinbox_var: Links the IntVar to the Spinbox
widget.spinbox_var.trace_add("write", update_label): Traces changes to the variable and
calls the update_label function when the variable's value changes.DoubleVarDoubleVar is used to manage floating-point values in widgets such as Scale,
etc.
Example:
import tkinter as tk
def update_label(*args):
label.config(text=f"Value: {scale_var.get():.2f}")
# Create the main window
root = tk.Tk()
root.title("DoubleVar Example")
root.geometry("300x200")
# Create a DoubleVar
scale_var = tk.DoubleVar()
# Create a Scale widget
scale = tk.Scale(root, from_=0.0, to=1.0, orient="horizontal", resolution=0.01, variable=scale_var)
scale.pack(pady=20)
# Create a Label widget
label = tk.Label(root, text="Value: 0.00")
label.pack(pady=10)
# Trace the variable to update the label when scale changes
scale_var.trace_add("write", update_label)
# Run the application
root.mainloop()
scale_var = tk.DoubleVar(): Creates a DoubleVar instance.variable=scale_var: Links the DoubleVar to the Scale
widget.scale_var.trace_add("write", update_label): Traces changes to the variable and
calls the update_label function when the variable's value changes.BooleanVarBooleanVar is used to manage boolean values in widgets such as Checkbutton,
etc.
Example:
import tkinter as tk
def update_label(*args):
label.config(text=f"Checked: {check_var.get()}")
# Create the main window
root = tk.Tk()
root.title("BooleanVar Example")
root.geometry("300x200")
# Create a BooleanVar
check_var = tk.BooleanVar()
# Create a Checkbutton widget
checkbutton = tk.Checkbutton(root, text="Check me", variable=check_var)
checkbutton.pack(pady=20)
# Create a Label widget
label = tk.Label(root, text="Checked: False")
label.pack(pady=10)
# Trace the variable to update the label when checkbutton changes
check_var.trace_add("write", update_label)
# Run the application
root.mainloop()
check_var = tk.BooleanVar(): Creates a BooleanVar instance.variable=check_var: Links the BooleanVar to the
Checkbutton widget.
check_var.trace_add("write", update_label): Traces changes to the variable and
calls the update_label function when the variable's value changes.Tkinter variables (StringVar, IntVar, DoubleVar,
BooleanVar) provide common methods for getting and setting their values.
get(): Returns the current value of the variable.set(value): Sets the variable to a new value.trace_add(mode, callback): Adds a callback to be executed when the variable
changes.trace_remove(mode, callback): Removes the callback.Example: Using get() and set() Methods
import tkinter as tk
# Create the main window
root = tk.Tk()
root.title("Get and Set Example")
root.geometry("300x200")
# Create a StringVar
entry_var = tk.StringVar()
# Create an Entry widget
entry = tk.Entry(root, textvariable=entry_var)
entry.pack(pady=20)
# Create a Label widget
label = tk.Label(root, text="Type something above")
label.pack(pady=10)
# Button to show the current value
def show_value():
label.config(text=f"Current value: {entry_var.get()}")
button_show = tk.Button(root, text="Show Value", command=show_value)
button_show.pack(pady=5)
# Button to set a new value
def set_value():
entry_var.set("New Value")
button_set = tk.Button(root, text="Set Value", command=set_value)
button_set.pack(pady=5)
# Run the application
root.mainloop()
entry_var.get(): Gets the current value of entry_var.entry_var.set("New Value"): Sets the value of entry_var to "New
Value".Tkinter variables (StringVar, IntVar, DoubleVar,
BooleanVar) are powerful tools for managing widget values dynamically. They provide
methods like get(), set(), and trace_add() to facilitate
interaction and automatic updates between widgets and variables. Using these variable classes can
help you create responsive and interactive Tkinter applications.