How to Reveal in Finder or simply Open the folder on Mac

Question

I'm sure this is possible but I feel you need to know more about shell commands on a mac than I do!
so can anyone fill in the blanks?
on revealfile filename
  if the platform contains "win" then
    err= bashell("open","explorer.exe",  "/select, " & filename, "", "normal")
  else
  end if
  return err
end
on openfolder foldername
  if the platform contains "win" then
    err= baShell( "open", plat(getosdirectory() & ":explorer.exe"), foldername, "", "normal" )
  else
  end if
  return err
end
many thanks

Answer 1

for the record, that daft line about put baactivewindow() doesn't work - but this does
on revealfile filename
if the platform contains "mac" then
    foldername=getfolder(filename) --anyone wanting to use this, you have to write a 'getfolder from filename' handler for this to work
    sendkeys=getfilename(filename) --you have to write a 'getfilename from filename' handler for this to work
    open foldername with "finder.app"
    result=baWaitForWindow(baActiveWindow(),"Active",300)
    result=basendkeys(sendkeys)
  else
    err= bashell("open","explorer.exe",  "/select, " & filename, "", "normal")
  end if
  return err
end