multiple apps: use argparse to support standard -h help

- group-lines
- qgifview
- password-prompt
- tailsleep

group-lines/group-lines

@@ -1,11 +1,15 @@
 #!/usr/bin/env python3
 # SPDX-License-Identifier: WTFPL
 
+import argparse
 import re
-import sys
 
 
-pattern = re.compile(sys.argv[1])
+parser = argparse.ArgumentParser()
+parser.add_argument("pattern")
+args = parser.parse_args()
+
+pattern = re.compile(args.pattern)
 
 groups = {}
 

password-prompt/password-prompt

@@ -3,13 +3,14 @@
 
 # reads a password on TTY (not stdin) and show it on stdout
 
+import argparse
 import getpass
-import sys
 
 
-try:
-    prompt = f"{sys.argv[1].rstrip()} "
-except IndexError:
-    prompt = "Password: "
+parser = argparse.ArgumentParser()
+parser.add_argument("prompt", default="Password:", nargs="?")
+args = parser.parse_args()
+
+prompt = f"{args.prompt.rstrip()} "
 
 print(getpass.getpass(prompt))

qgifview/qgifview

@@ -13,7 +13,7 @@ from PyQt5.QtWidgets import QApplication, QLabel
 app = QApplication(sys.argv)
 
 args = app.arguments()
-if len(args) != 2:
+if len(args) != 2 or sys.argv[1] in {'-h', '--help'}:
     print('usage: %s FILE.GIF' % args[0], file=sys.stderr)
     sys.exit(1)
 

tailsleep/tailsleep

@@ -12,20 +12,20 @@ def read_file(filename,
               sleep_time=1, end_after_inactivity_iter=5,
               suggested_block_size=4096):
 	"""Generates data of a growing file.
-	
+
 	Yields blocks of data.
 	When file end is reached, it waits `sleep_time` seconds
 	`end_after_inactivity_iter` times. If file has no more data within
 	that period, the generator ends.
 	"""
-	
+
 	def _read_some():
 		for _ in range(end_after_inactivity_iter):
 			block = f.read(suggested_block_size)
 			if block:
 				return block
 			time.sleep(sleep_time)
-	
+
 	with open(filename, 'rb') as f:
 		while True:
 			block = _read_some()
@@ -42,7 +42,7 @@ def _quit(signum, stack):
 def main():
 	locale.setlocale(locale.LC_ALL, '')
 
-	if len(sys.argv) != 2:
+	if len(sys.argv) != 2 or sys.argv[1] in {'-h', '--help'}:
 		print('usage: %s FILE' % sys.argv[0], file=sys.stderr)
 		sys.exit(os.EX_USAGE)