Pass variable from one function to another

Hello all,

I've read all the related topics, didn't find one to my question, so here it is

Consider this scenario:

;main au3 file

Opt("GuiOnEventMode", 1)

$main=GUICreate("Test", 200, 200)

$ticket_gui_btn = GUICtrlCreateButton("Ticket GUI", 10, 10, 50, 30)

GUICtrlSetOnEvent(-1, "ticket_gui")

#include <ticket.au3>

GUISetState(@SW_SHOW)

While 1
Sleep(1000) ;Idle around
WEnd

func close_func()
;bla bla bla
endFunc

;another file: ticket.au3

Func ticket_gui()

$child_gui = GUICreate("Test", 200, 200)

GUISetOnEvent($GUI_EVENT_CLOSE, "close_func")

$ticket_input = GUICtrlCreateInput("", 10, 10, 140, 23)

$send = GUICtrlCreateButton("Send", 10, 40 , 90, 25)
GUICtrlSetOnEvent(-1, "verify_gui")

GUISetState (@SW_SHOW, $child_gui)

endFunc

Func verify_gui()

$ticket_value=GUICtrlRead($ticket_input, 1)

if ticket_value="" then
msgbox(0, "error", "Ticket is empty")
endif

endFunc

If i declare the $ticket_input as a global variables outside the 2 functions, the variable $ticket_input is visible in the verify_gui() function and it works fine of course

My question: Is there an alternative instead of declaring it as a global variable?

PS: i have to many child windows and variables. And functions (gui and the verification ones) must be separate as the example above

Thanks guys

Update

For the ones who are suggestion using global variables, i'm already using that, i'm looking for an alternative solution
Using a message loop won't work since i'm using

Opt("GuiOnEventMode", 1)

If using global variables is the solution so be it, but i would like to read your opinion