Passing parameters

Hi board,

{Flash MX 2004 Pro}

[AS]
myMovieClip_mc.onPress = foo(true);

function foo(state:Boolean) {
// Do something
}
[/AS]
The above does not work. Infact the function is not even called.
How can I pass parameters to such functions.
I dont wanna do the following:
[AS]
myMovieClip_mc.onPress = function(true) {
// Do something
}
[/AS]

Thanks in advance,

Cruiser