Return a pointer to user-supplied data stored with a Channel
Description:
This macro is intended to be used within the source or sink functions
associated with a Channel. It returns any pointer previously stored in the
Channel (that is, the Channel that has invoked the source or sink function) using
astPutChannelData.
This mechanism is a thread-safe alternative to passing file
descriptors, etc, via static global variables.
Synopsis
void
∗astChannelData
Applicability
Channel
This macro applies to all Channels.
Returned
Value
astChannelData
The pointer previously stored with the Channel using
astPutChannelData. A NULL pointer will be returned if no such pointer has been stored
with the Channel.
Notes:
This routine is not available in the Fortran 77 interface to the AST library.