def arg_check():
'''Check and convert the command line argument(s).
'''
#-- 1 --
# [ arg_list := the command line arguments ]
arg_list = sys.argv[1:]
#-- 2 --
# [ if (len(arg_list)==1) and arg_list[0] is a valid
# date-time string ->
# dt := that date-time as a datetime.datetime instance
# else if (len(arg_list)==2) and (arg_list[0] is a valid
# date) and (arg_list[1] is a valid time) ->
# dt := a datetime.datetime representing that date
# and time
# else ->
# sys.stderr +:= error message
# stop execution ]
if len(arg_list) == 1:
try:
dt = sdr.parse_datetime(arg_list[0])
except SyntaxError, detail:
usage('Invalid date-time: {detail}'.format(detail=detail))
# else ->
# sys.stderr +:= error message
# stop execution ]
try:
lon = sdr.parse_lon(raw_lon)
except SyntaxError, detail:
usage('Invalid longitude: {detail}'.format(detail=detail))
#-- 5 --
# [ if raw_dt is a valid date-time string ->
# dt := that date-time as a datetime.datetime instance
# else ->
# sys.stderr +:= error message
# stop execution ]
try:
dt = sdr.parse_datetime(raw_dt)
except SyntaxError, detail:
usage('Invalid timestamp: {detail}'.format(detail=detail))
#-- 6 --
lat_lon = sdr.lat_lon(lat, lon)
return (ra_dec, lat_lon, dt)
#--- usage
def usage(*L):
'''Print a usage message and stop.
[ L is a list of strings ->
sys.stderr +:= (usage message) + (elements of L,
concatenated)
stop execution ]
