How to pass data in the extension from one method to another method?

Hi,

I’m writing an extension which uses two hooks and I need to pass some data from a function attached to one hook to the function attached to another hook.

I thought that this could be done passing some variable to $SESS->cache in one function as here

$SESS->cache['my_class_name']['_my_variable_name'] = $my_variable;

and later taking its value in another function as here

$my_variable = $SESS->cache['my_class_name']['_my_variable_name'];

but found that this does not work.

Does $SESS->cache cannot be used for passing data from one method to another in extension? Or I try to use it incorrectly?

Or to pass data from one method to another one necessarily should use a database table?

Thanks in advance.