I always asssign functions with zero parameters to buttons. I dont know why you would wanna have different buttons which call the same function, but if you still want to differentiate between them, you could bind delegates to your different buttons: e.g. CallButton_1 and CallButton_2 and these functions call your handleInventoryButtonPress with given button.
e.g.
void CallButton_2() {
handleInventoryButtonPress(Button_2,…);
}