Accessing var in base from declared type

init.pp

class foo (
  $testvalue  = $foo::params::testvalue,
) inherits foo::params {
  
  foo::somefunc { 'blah': }

}

params.pp

class foo::params {
  $testvalue = "Hello World"
}

somefunc.pp

define foo:somefunc {
  notice('Printing testvalue: $foo::testvalue')
}