How set a while with a function

a. from the return

function dosome(){ return true; }
OR
function dosome( param = true ){ return param; }

var = dosome();
while ( var ){ need(); }

b. while loop from fixed param TRUE

function need( $param = true) {

  while ( param ){
    $updates = get_point();
    echo  $updates['selector']; 
    echo 'done';
  }                                           

}
need();

c. while loop from fixed param FALSE

function need( $param = false) {

  while ( param ){
    $updates = get_point();
    echo  $updates['selector']; 
    echo 'done';
  }                                           

}
var = true;
need( var );