A TclOO question (for experts?)

Hello out there,
look at the following sample:
---
catch {Sample destroy}

oo::class create Sample {
    variable classVar ;# automatically exists in every instance
    constructor {someVar} {
        my variable objVar
        set classVar $someVar
        set objVar 99
    }
    destructor {
        my variable objVar classVar
        puts "classVar: $classVar, objVar: $objVar"
    }
}

Sample create s1 100
Sample create s2 200
s1 destroy ;# -> classVar: 100, objVar: 99
s2 destroy ;# -> classVar: 200, objVar: 99
---
My question is: What happens, if I add 'classVar', although not
needed, to a 'my variable' statement  - like I did in the destructor
above. Is it just superfluous or can it have consequences in a more
complex situation than the above example.
Thank you for any enlightenment
Helmut