You can pass as the callback argument anything which is callable by PHP definition, something that might actually change between PHP versions.
In this specific case the array($o,$m)
type of notation indicates that the filter will call $o->$m
You can pass as the callback argument anything which is callable by PHP definition, something that might actually change between PHP versions.
In this specific case the array($o,$m)
type of notation indicates that the filter will call $o->$m