Access a Function Variable Outside the Function Without Using "Global"

Access a function variable outside the function without using global

You could do something along these lines (which worked in both Python v2.7.17 and v3.8.1 when I tested it/them):

def hi():
    # other code...
    hi.bye = 42  # Create function attribute.
    sigh = 10

hi()
print(hi.bye)  # -> 42

Functions are objects in Python and can have arbitrary attributes assigned to them.

If you're going to be doing this kind of thing often, you could implement something more generic by creating a function decorator that adds a this argument to each call to the decorated function.

This additional argument will give functions a way to reference themselves without needing to explicitly embed (hardcode) their name into the rest of the definition and is similar to the instance argument that class methods automatically receive as their first argument which is usually named self — I picked something different to avoid confusion, but like the self argument, it can be named whatever you wish.

Here's an example of that approach:

def add_this_arg(func):
    def wrapped(*args, **kwargs):
        return func(wrapped, *args, **kwargs)
    return wrapped

@add_this_arg
def hi(this, that):
    # other code...
    this.bye = 2 * that  # Create function attribute.
    sigh = 10

hi(21)
print(hi.bye)  # -> 42

Note

This doesn't work for class methods. Just use the instance argument, named self by convention, that's already passed to methods instead of the method's name. You can reference class-level attributes through type(self). See Function's attributes when in a class.

Accessing variables outside method call on an object without making them global (is it possible?)

Myself, I'd keep them in one place, without polluting the scope:

MyObject.prototype.template = function(){ 
    this.params = {all: '', these: '', variables: '', etc: ''}
    for (var i=0; i<10; i++){
        callback();
}};

MyObject.prototype.myFirstMethod = function(){ 
    var self = this;
    this.template(function(){
        console.log(self.params);
    });
};

Access variable from a different function from another file

You can access the value of a variable in a function by 1) returning the value in the function, 2) use a global variable in the module, or 3) define a class.

If only want to access a single variable local to a function then the function should return that value. A benefit of the class definition is that you may define as many variables as you need to access.

1. Return value

def champs_info(champname:str, tier_str:int):  
    ...
    tier = tier_access.text
    return tier

2. global

tier = None
def champs_info(champname:str, tier_str:int):
    global tier
    ...
    tier = tier_access.text

Global tier vairable is accessed.

from mypythonlib import myfunctions

def test_champs_info():
    myfunctions.champs_info("abomination", 6)
    return myfunctions.tier

print(test_champs_info())

3. class definition:

class Champ:
    def __init__(self):
        self.tier = None
    def champs_info(self, champname:str, tier_str:int):  
        ...
        self.tier = tier_access.text

test_functions.py can call champs_info() in this manner.

from mypythonlib import myfunctions

def test_champs_info():
    info = myfunctions.Champ()
    info.champs_info("abomination", 6)
    return info.tier
    
print(test_champs_info())

Python - Change variable outside function without return

Here's a simple (python 2.x) example of how to 1 not use globals and 2 use a (simplistic) domain model class.

The point is: you should first design your domain model independently from your user interface, then write the user interface code calling on your domain model. In this case your UI is a Tkinter GUI, but the same domain model should be able to work with a command line UI, a web UI or whatever.

NB : for python 3.x, replace Tkinter with tkinter (lowercase) and you can get rid of the object base class for Model.

import random
from Tkinter import *

class Model(object):
    def __init__(self):
        self.currentMovie = 0

    def UpdateCurrentMovie(self):
        self.currentMovie = random.randint(0, 100)
        print(self.currentMovie)

    def UpdateWatched(self):
        print(self.currentMovie)

    def ExampleWithArgs(self, arg):
        print("ExampleWithArg({})".format(arg))

def main():
    model = Model()
    root = Tk()
    root.title("MovieSelector9000")
    root.geometry("900x600")
    app = Frame(root)
    app.grid()
    canvas = Canvas(app, width = 300, height = 75)
    canvas.pack(side = "left")
    button1 = Button(canvas, text = "SetRandomMovie", command=model.UpdateCurrentMovie)
    button2 = Button(canvas, text = "GetRandomMovie", command=model.UpdateWatched)
    button3 = Button(canvas, text = "ExampleWithArg", command=lambda: model.ExampleWithArgs("foo"))
    button1.pack(anchor = NW, side = "left")
    button2.pack(anchor = NW, side = "left")
    button3.pack(anchor = NW, side = "left")
    root.mainloop()

if __name__ == "__main__":
    main()

How to access a variable in one python function in another function

You have to declare the variable to be global, then use it. Like so:

def add_to_outside():
    global outside #say that it is global
    outside = 1 #now create it!

def see_it():
    global outside #say that it is global
    print(outside)

##As shown:
add_to_outside()
see_it()
#output: 1

The keyword global at the start makes all variables of that name in the function reference the global values. You don't say a variable is global and change it in the same statement.

Also, only put the global keyword at the start of the function. It doesn’t need to be next to the changes to the variables, and is only needed once.

To declare multiple variables global, do it like this:

global var1, var2, var3 #etc.

Accessing variables from other functions without using global variables

To make a variable calculated in function A visible in function B, you have three choices:

• make it a global,
• make it an object property, or
• pass it as a parameter when calling B from A.

If your program is fairly small then globals are not so bad. Otherwise I would consider using the third method:

function A()
{
    var rand_num = calculate_random_number();
    B(rand_num);
}

function B(r)
{
    use_rand_num(r);
}

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