Tweaked Python code to allow static type checking, without changing behavior.

python/qrcodegen-batch-test.py

@@ -25,6 +25,7 @@
 # 
 
 import itertools, random, subprocess, sys, time
+from typing import Optional, TypeVar
 
 
 CHILD_PROGRAMS = [
@@ -56,7 +57,7 @@ def main():
 		for proc in subprocs:
 			if proc.poll() is None:
 				print(-1, file=proc.stdin)
-				proc.stdin.flush()
+				not_none(proc.stdin).flush()
 		sys.exit("Error: One or more workers failed to start")
 	
 	# Do tests
@@ -120,15 +121,22 @@ def write_all(val):
 
 def flush_all():
 	for proc in subprocs:
-		proc.stdin.flush()
+		not_none(proc.stdin).flush()
 
 def read_verify():
-	val = subprocs[0].stdout.readline().rstrip("\r\n")
+	val = not_none(subprocs[0].stdout).readline().rstrip("\r\n")
 	for proc in subprocs[1 : ]:
-		if proc.stdout.readline().rstrip("\r\n") != val:
+		if not_none(proc.stdout).readline().rstrip("\r\n") != val:
 			raise ValueError("Mismatch")
 	return int(val)
 
 
+T = TypeVar("T")
+def not_none(obj: Optional[T]) -> T:
+	if obj is None:
+		raise TypeError()
+	return obj
+
+
 if __name__ == "__main__":
 	main()

python/qrcodegen.py

@@ -651,18 +651,18 @@ class QrCode:
 	_ECC_CODEWORDS_PER_BLOCK = (
 		# Version: (note that index 0 is for padding, and is set to an illegal value)
 		# 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40    Error correction level
-		(None,  7, 10, 15, 20, 26, 18, 20, 24, 30, 18, 20, 24, 26, 30, 22, 24, 28, 30, 28, 28, 28, 28, 30, 30, 26, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30),  # Low
+		(-1,  7, 10, 15, 20, 26, 18, 20, 24, 30, 18, 20, 24, 26, 30, 22, 24, 28, 30, 28, 28, 28, 28, 30, 30, 26, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30),  # Low
-		(None, 10, 16, 26, 18, 24, 16, 18, 22, 22, 26, 30, 22, 22, 24, 24, 28, 28, 26, 26, 26, 26, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28),  # Medium
+		(-1, 10, 16, 26, 18, 24, 16, 18, 22, 22, 26, 30, 22, 22, 24, 24, 28, 28, 26, 26, 26, 26, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28),  # Medium
-		(None, 13, 22, 18, 26, 18, 24, 18, 22, 20, 24, 28, 26, 24, 20, 30, 24, 28, 28, 26, 30, 28, 30, 30, 30, 30, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30),  # Quartile
+		(-1, 13, 22, 18, 26, 18, 24, 18, 22, 20, 24, 28, 26, 24, 20, 30, 24, 28, 28, 26, 30, 28, 30, 30, 30, 30, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30),  # Quartile
-		(None, 17, 28, 22, 16, 22, 28, 26, 26, 24, 28, 24, 28, 22, 24, 24, 30, 28, 28, 26, 28, 30, 24, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30))  # High
+		(-1, 17, 28, 22, 16, 22, 28, 26, 26, 24, 28, 24, 28, 22, 24, 24, 30, 28, 28, 26, 28, 30, 24, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30))  # High
 	
 	_NUM_ERROR_CORRECTION_BLOCKS = (
 		# Version: (note that index 0 is for padding, and is set to an illegal value)
 		# 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40    Error correction level
-		(None, 1, 1, 1, 1, 1, 2, 2, 2, 2, 4,  4,  4,  4,  4,  6,  6,  6,  6,  7,  8,  8,  9,  9, 10, 12, 12, 12, 13, 14, 15, 16, 17, 18, 19, 19, 20, 21, 22, 24, 25),  # Low
+		(-1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 4,  4,  4,  4,  4,  6,  6,  6,  6,  7,  8,  8,  9,  9, 10, 12, 12, 12, 13, 14, 15, 16, 17, 18, 19, 19, 20, 21, 22, 24, 25),  # Low
-		(None, 1, 1, 1, 2, 2, 4, 4, 4, 5, 5,  5,  8,  9,  9, 10, 10, 11, 13, 14, 16, 17, 17, 18, 20, 21, 23, 25, 26, 28, 29, 31, 33, 35, 37, 38, 40, 43, 45, 47, 49),  # Medium
+		(-1, 1, 1, 1, 2, 2, 4, 4, 4, 5, 5,  5,  8,  9,  9, 10, 10, 11, 13, 14, 16, 17, 17, 18, 20, 21, 23, 25, 26, 28, 29, 31, 33, 35, 37, 38, 40, 43, 45, 47, 49),  # Medium
-		(None, 1, 1, 2, 2, 4, 4, 6, 6, 8, 8,  8, 10, 12, 16, 12, 17, 16, 18, 21, 20, 23, 23, 25, 27, 29, 34, 34, 35, 38, 40, 43, 45, 48, 51, 53, 56, 59, 62, 65, 68),  # Quartile
+		(-1, 1, 1, 2, 2, 4, 4, 6, 6, 8, 8,  8, 10, 12, 16, 12, 17, 16, 18, 21, 20, 23, 23, 25, 27, 29, 34, 34, 35, 38, 40, 43, 45, 48, 51, 53, 56, 59, 62, 65, 68),  # Quartile
-		(None, 1, 1, 2, 4, 4, 4, 5, 6, 8, 8, 11, 11, 16, 16, 18, 16, 19, 21, 25, 25, 25, 34, 30, 32, 35, 37, 40, 42, 45, 48, 51, 54, 57, 60, 63, 66, 70, 74, 77, 81))  # High
+		(-1, 1, 1, 2, 4, 4, 4, 5, 6, 8, 8, 11, 11, 16, 16, 18, 16, 19, 21, 25, 25, 25, 34, 30, 32, 35, 37, 40, 42, 45, 48, 51, 54, 57, 60, 63, 66, 70, 74, 77, 81))  # High
 	
 	_MASK_PATTERNS = (
 		(lambda x, y:  (x + y) % 2                  ),
@@ -685,6 +685,12 @@ class QrCode:
 			self.ordinal = i  # (Public) In the range 0 to 3 (unsigned 2-bit integer)
 			self.formatbits = fb  # (Package-private) In the range 0 to 3 (unsigned 2-bit integer)
 		
+		# Placeholders
+		LOW     : QrCode.Ecc
+		MEDIUM  : QrCode.Ecc
+		QUARTILE: QrCode.Ecc
+		HIGH    : QrCode.Ecc
+	
 	# Public constants. Create them outside the class.
 	Ecc.LOW      = Ecc(0, 1)  # The QR Code can tolerate about  7% erroneous codewords
 	Ecc.MEDIUM   = Ecc(1, 0)  # The QR Code can tolerate about 15% erroneous codewords
@@ -883,6 +889,13 @@ class QrSegment:
 			in a QR Code at the given version number. The result is in the range [0, 16]."""
 			return self._charcounts[(ver + 7) // 17]
 		
+		# Placeholders
+		NUMERIC     : QrSegment.Mode
+		ALPHANUMERIC: QrSegment.Mode
+		BYTE        : QrSegment.Mode
+		KANJI       : QrSegment.Mode
+		ECI         : QrSegment.Mode
+	
 	# Public constants. Create them outside the class.
 	Mode.NUMERIC      = Mode(0x1, (10, 12, 14))
 	Mode.ALPHANUMERIC = Mode(0x2, ( 9, 11, 13))