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This function does all checking of command line
arguments, and boils them down to a datetime.datetime instance.
# - - - a r g C h e c k
def argCheck():
"""Check and convert the command line argument(s).
"""
The command line arguments in sys.argv[1:]
can take either of two forms:
A single argument, consisting of an ISO standard
date, optionally followed by letter “T” (in either case) and a time, which
may omit minutes and seconds; or,
Two arguments: the first is an ISO date, and the
second is the time in the same form as part after the
“T” in the
single-argument case.
In the first case, we use Section 9.6, “parseDatetime(): Convert an external
date-time string” to parse the single argument; in the second, we use
Section 9.7, “parseDate(): Convert an external date
string” and Section 9.8, “parseTime(): Convert an external time
string” and then combine them into a datetime.datetime instance.
#-- 1 --
# [ argList := the command line arguments ]
argList = sys.argv[1:]
#-- 2 --
# [ if (len(argList)==1) and argList[0] is a valid
# date-time string ->
# dt := that date-time as a datetime.datetime instance
# else if (len(argList)==2) and (argList[0] is a valid
# date) and (argList[1] is a valid time) ->
# dt := a datetime.datetime representing that date
# and time
# else ->
# sys.stderr +:= error message
# stop execution ]
if len(argList) == 1:
try:
dt = sidereal.parseDatetime ( argList[0] )
except SyntaxError, detail:
usage ( "Invalid date-time: %s" % detail )
elif len(argList) == 2:
try:
date = sidereal.parseDate ( argList[0] )
except SyntaxError, detail:
usage ( "Invalid date: %s" % detail )
try:
time = sidereal.parseTime ( argList[1] )
except SyntaxError, detail:
usage ( "Invalid time: %s" % detail )
dt = date.combine ( date, time )
else:
usage ( "Incorrect number of arguments." )
#-- 3 --
return dt