I think you're missing the point, the pseudo-code id consider more or less equivelent to what BrowserUK wrote is:

#$obj->thing( 15000, 20000 ) =~ s[something][else]g;
{
  my $tmp=$obj->thing();
  $tmp =~ s[something][else]g;
  $obj->thing(15000,20000,$tmp);
}
[download]

I suspect we could debate about exactly how this one should perform (omitting the arguments its easy but whether the arguments belong to the setter, the getter or both is a debate probably worth having.)