Update crc32.py.

crc32.py

@@ -1,11 +1,33 @@
+import argparse
 import sys
 import zlib
 
+from voussoirkit import pipeable
 from voussoirkit import winglob
 
-patterns = sys.argv[1:]
-files = [file for pattern in patterns for file in winglob.glob(pattern)]
+def crc32_argparse(args):
+    files = (
+        file
+        for arg in args.source
+        for pattern in pipeable.input(arg)
+        for file in winglob.glob(pattern)
+    )
     for file in files:
+        try:
             with open(file, 'rb') as handle:
                 crc = zlib.crc32(handle.read())
             print(hex(crc)[2:].rjust(8, '0'), file)
+        except Exception as e:
+            print(file, e)
+
+def main(argv):
+    parser = argparse.ArgumentParser(description=__doc__)
+
+    parser.add_argument('source', nargs='+')
+    parser.set_defaults(func=crc32_argparse)
+
+    args = parser.parse_args(argv)
+    return args.func(args)
+
+if __name__ == '__main__':
+    raise SystemExit(main(sys.argv[1:]))