Associates a function with group which will be called from OptionContext.parse when an error occurs.
Note that the user data to be passed to error_func can be specified when constructing the group with OptionGroup.new.
a function to call when an error occurs
2.6
Associates a function with group which will be called from OptionContext.parse when an error occurs.
Note that the user data to be passed to error_func can be specified when constructing the group with OptionGroup.new.