Class HeaderProcessor

source code

   object --+    
            |    
FileProcessor --+
                |
               HeaderProcessor

A base for processors doing FITS header manipulations.

The processor builds naked FITS headers alongside the actual files, with an added extension .hdr (or whatever is in the headerExt attribute). The presence of a FITS header indicates that a file has been processed. The headers on the actual FITS files are only replaced if necessary.

The basic flow is: Check if there is a header. If not, call _getNewHeader(srcFile) -> hdr. Store hdr to cache. Insert cached header in the new FITS if it's not there yet.

You have to implement the _getHeader(srcName) -> pyfits header object function. It must raise an exception if it cannot come up with a header. You also have to implement _isProcessed(srcName) -> boolean returning True if you think srcName already has a processed header.

This basic flow is influenced by the following opts attributes:

• reProcess -- even if a cache is present, recompute header values
• applyHeaders -- actually replace old headers with new headers
• reHeader -- even if _isProcessed returns True, write a new header
• compute -- perform computations

The idea is that you can:

• generate headers without touching the original files: proc
• write all cached headers to files that don't have them proc --apply --nocompute
• after a bugfix force all headers to be regenerated: proc --reprocess --apply --reheader

All this leads to the messy logic. Sorry 'bout this.