The best way to call multiple values in a function from another function in Python

Question

As I working with the Python tkinter GUI and sqlite 3 recently to build a project, I discovered a lots of questions in Python programming. One of the questions is what would be the best way of calling multiple values in a function from another function in python? Meanwhile, I've done some research about retuning and calling value in function, and I know that in python function it can allows to return multiple value, however, when it comes to calling and I want it to call specifically the value I return e.g return (x,y,z), I really not sure how could I call it.

Here are some code that are in my project, please feel free to give me any suggestion about my code and the question that I ask above

First function

def taskUpdateB():
    conn = sqlite3.connect("zzzsqlite.db")
    booking = conn.cursor()

    index = sOLB.curselection()
    selTask = sOLB.get(index)
    bookinID = selTask[-2]

    getBookID = booking.execute('''SELECT bookingID FROM booking 
                        WHERE bookingID=?''', (bookinID,))    

    taUp = Toplevel()
    taUp.title("Task Update")
    taskLabel = Label(taUp, text ="Task Update", font=('Times', 20))
    taskLabel.grid(row=0)

    showLabel = Label(taUp, text ="Please Select and Enter Infomation Below", font=('Times', 18))
    showLabel.grid(row=1)

    var = IntVar()
    var = 0
    fullRadio = Radiobutton(taUp, text="Fully", variable=var, value=1, command = taskUpdCom)
    fullRadio.grid(row=2, sticky=W)

    partRadio = Radiobutton(taUp, text="Partly", variable=var, value=2, command = taskUpdCom)
    partRadio.grid(row=3, sticky=W)

    notRadio = Radiobutton(taUp, text="Unable", variable=var, value=3, command = taskUpdCom)
    notRadio.grid(row=4, sticky=W)

    noteLabel = Label(taUp, text ="Note:", font=('Times', 16))
    noteLabel.grid(row=5, sticky=W)
    noteBox = Text(taUp, width=30, height =20, font=('Arial', 12,), highlightbackground='black')
    noteBox.grid(row=6)

    comButton = Button(taUp, text ="Task Complete and Send Invoice", command = taskUpdCom)
    comButton.grid(row =7)

    booking.close()
    return (var, noteBox, showLabel, bookinID)

Second function

 def taskUpdCom():
        a = taskUpdateB
        #get the data from the update list
        var = taskUpdateB.var()
        noteBox = taskUpdateB.noteBox()
        showLabel = taskUpdateB.showLabel()
        bookinID = taskUpdateB.bookinID()

    selProg = str(var.get())
    if selProg == 0:
        showLabel["text"] = ("***Please Select Task Progress Below***")
    elif noteBox.get() == "":
        showLabel["text"] = ("***Please Enter Task Note Below***")
    else:
        conn = sqlite3.connect("zzzsqlite.db")
        update = conn.cursor()
        wriUpda = zzzsqliteTable.addUpdate(bookinID, selProg, noteBox)
        conn.commit()
        updata.close()
        taskUpdateB.noteBox.delete(0, END)
        tkinter.messagebox.showinfo("Notification","Your task has been updated and removed from the list")
        try:
            deIndex = taskUpdateB.index()#The item selected from task update delete it from the list.... will still in the database.
            sOLB.delete(deIndex)
        except IndexError:
            pass

Please forgive my code has not been fully complete yet, and kind of messy...

Thanks for your help :)

@Joel Cornett sorry for my language, calling a function which contain x value — PyJar
– PyJar, Commented Apr 15, 2013 at 20:38
Functions don't "contain" values. Functions produce return values. — Silas Ray
– Silas Ray, Commented Apr 15, 2013 at 20:39
I'm not sure you quite get that difference, actually. You seem to have the idea that the function is an execution container that holds the results within itself that you can then access. That's a fundamental conceptual misunderstanding. — Silas Ray
– Silas Ray, Commented Apr 15, 2013 at 20:43

Silas Ray · Accepted Answer · 2013-04-15 20:37:53Z

5

That's not how functions work. You probably want to call the function then unpack the results in the calling scope.

var, noteBox, showLabel, bookinID = taskUpdateB()

While it is true that functions are objects in Python, they aren't stateful processors or something, they just return the result directly and then disappear (well, unless you are doing something fancy, but you aren't).

answered Apr 15, 2013 at 20:37

Silas Ray

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9 Comments

Joel Cornett Over a year ago

You could also use the splat operator and unpack the values of taskUpdateB() as the arguments for taskUpdCom().

Silas Ray Over a year ago

True, though he'd have to restructure a little bit and do that from the driver instead of in taskUpdCom.

PyJar Over a year ago

@sr2222 Thanks for your solution, is that all it needs? do I need to covert it to an variable e.g value = var in order to call it in the second function?

Silas Ray Over a year ago

He means the asterisk. Python has a shorthand for unpacking an iterable in to an argument list for a function. If you moved the call to taskUpdateB out of taskUpdCom, you could change the signature of taskUpdCom to expect 4 arguments, then just say taskUpdCom(*taskUpdateB()) from the outer calling scope.

Silas Ray Over a year ago

That's a different, and less specific question. You should really focus on getting down the fundamentals of how functions work. I think you've built up an incorrect understanding from your experience with object oriented libraries for DB and UI interaction before getting a firm foundation in basic functional programming. You need to understand the basics of passing values to and from functions before worrying about syntactical sugar like argument unpacking.

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