JSON Pretiffier

#!/usr/bin/env python
'''JSON prettifier'''

def shift(array):
   try:
       return array.pop(0)
   except IndexError:
       return None

def fopen(name, mode, default):
   if name in (None, "-"):
       return default
   return open(name, mode)

def main(argv=None):
   import sys
   from optparse import OptionParser

   argv = argv or sys.argv

   indent = 4
   parser = OptionParser("%prog [INFILE [OUTFILE]]")
   parser.add_option("-i", "--indent", help="indent size (%s)" % indent,
                     dest="indent", default=indent, type="int")
   opts, args = parser.parse_args(argv[1:])
   if len(args) not in (0, 1, 2):
       parser.error("wrong number of arguments") # Will exit

   try:
       info = fopen(shift(args), "r", sys.stdin)
       outfo = fopen(shift(args), "w", sys.stdout)
   except IOError, e:
       raise SystemExit("error: %s" % e)

   import json
   json.dump(json.load(info), outfo, indent=opts.indent)
      
if __name__ == "__main__":
   main()

Update (Aug 14, 2009): Just found out about python -mjson.tool, oh well ...