Setting default variable

[Zeev Fisher]

Hi All,

I would like to declare default variable and then overwrite it only if some class is true for the host. 

Current way that I know to implement it is :

!Classname::

        variable = default

Classname::

        variable = variable_value

This way I need all the time to add to the list of exclude new classes.
What I need is to have default value and only if there's a need to define other value , it will be defined

Thanks a lot
Zeev