Can I use a function to return a default param in php?

Question

I would like to do something like this:

function readUser($aUser = loadDefaultUser()){

 //doing read User
}

I find that it will display a erro

Answer 1

I would rather give a Null value for this argument and then call loadDefaultUser() in the body of the function. Something like this:

function readUser($aUser = NULL){
    if(is_null($aUser)){
        $aUser = loadDefaultUser();
    }
    //...
}