OldValue property for wx.ComboBox?

On EVT_COMBOBOX trigger, I first need to perform some operations based on the old value of combo box.

ie when combo box selection changes from ‘a’ to ‘b’, I need to save ‘a’ before I go to ‘b’.

Is this possible?

I did a work around using a class variable to hold the old value, but wondering if there is a better way.