tools: update sdwrap.py to use Python3.8 features

tools/zos/sdwrap.py

@@ -1,82 +1,68 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import argparse
 import sys
 
 def wrap(args):
-  l = args.input.readline(72)
   firstline = True
-  while l:
-    if l[-1] == '\n':
+  while (line := args.input.read(72)):
+    if line.endswith('\n'):
       if firstline:
-        outstr = "{}".format(l)
+        outstr = f"{line}"
       else:
-        outstr = " {}".format(l)
+        outstr = f" {line}"
         firstline = True
-      l = args.input.readline(72)
     else:
       if firstline:
-        outstr = "{:<71}*\n".format(l[:-1])
+        outstr = f"{line:<71}*\n"
         firstline = False
       else:
-        outstr = " {:<70}*\n".format(l[:-1])
-      l = l[-1] + args.input.readline(70)
+        outstr = f" {line:<70}*\n"
+      line = line[-1] + args.input.read(70)
     args.output.write(outstr)
-
   return 0
 
 def unwrap(args):
-  l = args.input.readline()
   firstline = True
-  while l:
-    if len(l) > 80:
+  for line in args.input:
+    if len(line) > 80:
       print("Error: input line invalid (longer than 80 characters)", file=sys.stderr)
       return 1
-    if not firstline and l[0] != ' ':
-      print("Error: continuation line not start with blank", file=sys.stderr)
+    if not firstline and line[0] != ' ':
+      print("Error: continuation line does not start with a blank", file=sys.stderr)
       return 1
 
-    if len(l) > 71 and l[71] == '*':
+    if len(line) > 71 and line[71] == '*':
       if firstline:
-        args.output.write(l[:71])
+        args.output.write(line[:71])
         firstline = False
       else:
-        args.output.write(l[1:71])
+        args.output.write(line[1:71])
     else:
       if firstline:
-        args.output.write(l)
+        args.output.write(line)
       else:
-        args.output.write(l[1:])
+        args.output.write(line[1:])
         firstline = True
-    l = args.input.readline()
   return 0
 
-def Main():
+def main():
   parser = argparse.ArgumentParser(description="Wrap sidedeck source to card formats")
-  parser.add_argument("-u", "--unwrap",
-      help="Unwrap sidedeck cards to source formats instead", action="store_true",
-      default=False)
-  parser.add_argument("-i", "--input", help="input filename, default to stdin",
-      action="store", default=None)
-  parser.add_argument("-o", "--output", help="output filename, default to stdout",
-      action="store", default=None)
+  parser.add_argument("-u", "--unwrap", help="Unwrap sidedeck cards to source formats instead", action="store_true")
+  parser.add_argument("-i", "--input", help="Input filename, defaults to stdin", default=None)
+  parser.add_argument("-o", "--output", help="Output filename, defaults to stdout", default=None)
 
   args = parser.parse_args()
 
-  if args.input is None:
-    args.input = sys.stdin
-  else:
-    args.input = open(args.input, 'r')
-
-  if args.output is None:
-    args.output = sys.stdout
-  else:
-    args.output = open(args.output, 'w')
+  with open(args.input, 'r') if args.input else sys.stdin as infile, \
+       open(args.output, 'w') if args.output else sys.stdout as outfile:
 
-  if args.unwrap:
-    return unwrap(args)
+    args.input = infile
+    args.output = outfile
 
-  return wrap(args)
+    if args.unwrap:
+      return unwrap(args)
+    return wrap(args)
 
 if __name__ == '__main__':
-  sys.exit(Main())
+  sys.exit(main())