Python equivalent of #line?

[Jeff Epler]

If you are printing your own tracebacks, you could add your own machinery
to interpret '#line' directives in the .py file.  This would be possible
because '#line' will obviously be treated as a comment by Python itself.
See traceback.py for how this is currently done.  It seems that in each
place (filename,lineno) is used, you'll need to put a call to your new
function:

	# You write this function
	def find_origin_line(filename, lineno):
		"""return the originating filename and line-number for this
		   possibly-preprocessed Python file"""
		...

	# and change these functions
	def print_tb(tb, limit=None, file=None):
	    """Print up to 'limit' stack trace entries from the traceback 'tb'.

	    If 'limit' is omitted or None, all entries are printed.  If 'file'
	    is omitted or None, the output goes to sys.stderr; otherwise
	    'file' should be an open file or file-like object with a write()
	    method.
	    """
	    if not file:
		file = sys.stderr
	    if limit is None:
		if hasattr(sys, 'tracebacklimit'):
		    limit = sys.tracebacklimit
	    n = 0
	    while tb is not None and (limit is None or n < limit):
		f = tb.tb_frame
		lineno = tb_lineno(tb)
		co = f.f_code
		filename = co.co_filename
		filename, lineno = find_origin_line(filename, lineno)   # XXX and similarly elsewhere
		name = co.co_name
		_print(file,
		       '  File "%s", line %d, in %s' % (filename,lineno,name))
		line = linecache.getline(filename, lineno)
		if line: _print(file, '    ' + line.strip())
		tb = tb.tb_next
		n = n+1
		
Jeff