Take advantage of the automatic file handling thinfy in argparser

src/main-export-known-hosts.py

@@ -34,10 +34,13 @@ def main():
 
 	# -o can be used to write the .sshwot thing to a file instead of stdout
 	parser.add_argument('-o',
-		# We store one argument given after this one to the property
-		# outfile, which will be None otherwise
+		# Given one argument, we open a file of that name and store it
+		# to outfile, which will be sys.stdout.buffer otherwise.
+		# We use .buffer since we're going to write binary data
 		action = 'store',
 		dest = 'outfile',
+		type = argparse.FileType('wb'),
+		default = sys.stdout.buffer,
 		# This is what will be displayed in the help after -o
 		metavar = 'outfile',
 		help = 'write the sshwot file to a given file instead of the stdout'
@@ -68,15 +71,7 @@ def main():
 	for known_hosts_entry in known_host_entries:
 		entries.append(process_known_hosts.known_hosts_to_entry(known_hosts_entry))
 
-	if args.outfile is None:
-		# Write to stdout by default
-		# We use sys.stdout.buffer instead of just sys.stdout because we
-		# are writing binary data
-		write_file.write(sys.stdout.buffer, entries)
-
-	else:
-		with open(args.outfile, 'wb') as outf:
-			write_file.write(outf, entries)
+	write_file.write(args.outfile, entries)
 
 if __name__ == '__main__':
 	try: