The pointer returned by astReadastRead (ยง15.4) could
identify any class of ObjectObject—this is determined entirely by the
external data being read. If it is necessary to test for a particular
class (say a FrameFrame), this may be done as follows using the appropriate
member of the astIsAClass
astIsA
Class
family of functions:
Note, however, that this will accept any Frame, so would be equally happy with a basic Frame or a SkyFrameSkyFrame. An alternative validation strategy would be to obtain the value of the Object's ClassClass attribute and then test this character string, as follows:
This would only accept a basic Frame and would reject a SkyFrame.