getopt

[Don Low]

Hi,

I'm going over a script that demonstrates the getopt function. I include
the script here:


#! /usr/bin/python

import sys, getopt, string

def help_message():
	print '''options.py -- uses getopt to recognize options
Options: -h      -- displays this help message
	-a      -- expects an argument
	--file= -- expects an argument
	--view  -- doesn't necessarily expect an argument
	--version -- displays Python version'''
	sys.exit(0)
	
try:
	options, xarguments = getopt.getopt(sys.argv[1:], 'ha', \
['file=', 'view=', 'version', 'python-version'])
except getopt.error:
	print '''Error: You tried to use an unknown option or the 
argument for an option that requires it was missing. Try 
`options.py -h\' for more information.'''
	sys.exit(0)
	
for a in options[:]:
	if a[0] == '-h':
		help_message()
		
for a in options[:]:
	if a[0] == '-a' and a[1] != '':
		print a[0]+' = '+a[1]
		options.remove(a)
		break
	elif a[0] == '-a' and a[1] == '':
		print '-a expects an argument'
		sys.exit(0)
		
for a in options[:]:
	if a[0] == '--file' and a[1] != '':
		print a[0]+' = '+a[1]
		options.remove(a)
		break
	elif a[0] == '--file' and a[1] == '':
		print '--file expects an argument'
		sys.exit(0)
		
for a in options[:]:
	if a[0] == '--view' and a[1] != '':
		print a[0]+' = '+a[1]
		options.remove(a)
		break
	elif a[0] == '--view' and a[1] == '':
		print '--view doesn\'t necessarily expect an argument...'
		options.remove(a)
		sys.exit(0)
		
for a in options[:]:
	if a[0] == '--version':
		print 'options version 0.0.001'
		sys.exit(0)
		
for a in options[:]:
	if a[0] == '--python-version':
		print 'Python '+sys.version
		sys.exit(0)

# END OF SCRIPT

When I execute the script with the -a option or the --view option as in:

./script_name -a myarg

It should report back:

-a = myarg

Instead it gives me:

-a expects an argument

This goes the same for the --file argument. The only one that works as
it should is the --view argument, as in:

./help2.py --view=myarg
--view = ssdt

This is because an equal sign (=) has been appended to 'view' when
getopt is called. If I add an equal sign to file (file=), it starts
working as it should too.

Can anyone explain this?

-- 
Thanks,

Don