doc: simplify function to compute SHA256 checksum, move function outside class AutogenDoc (documentation generator)

doc/docgen.py

@@ -57,7 +57,6 @@ try:
     import hashlib
     import os
     import re
-    import sys
     from collections import defaultdict
     from operator import itemgetter
 except ImportError as message:
@@ -141,6 +140,16 @@ IGNORE_COMPLETIONS_ITEMS = (
 )
 
 
+def sha256_file(filename, default=None):
+    """Return SHA256 checksum of a file."""
+    try:
+        with open(filename, 'rb') as _file:
+            checksum = hashlib.sha256(_file.read()).hexdigest()
+    except IOError:
+        checksum = default
+    return checksum
+
+
 class AutogenDoc(object):
     """A class to write auto-generated doc files."""
 
@@ -158,29 +167,14 @@ class AutogenDoc(object):
         """Write a line in auto-generated doc file."""
         self._file.write(string)
 
-    @staticmethod
-    def sha256_file(filename, default):
-        """
-        Return SHA256 checksum of a file, "default" if file is not found.
-        """
-        try:
-            with open(filename, 'r') as _file:
-                content = _file.read()
-                if sys.version_info >= (3, ):
-                    content = content.encode('utf-8')
-                checksum = hashlib.sha256(content).hexdigest()
-        except IOError:
-            checksum = default
-        return checksum
-
     def update(self, obj_name, num_files, num_files_updated):
         """Update doc file if needed (if content has changed)."""
         # close temp file
         self._file.close()
-        shaold = AutogenDoc.sha256_file(self.filename, 'old')
-        shanew = AutogenDoc.sha256_file(self.filename_tmp, 'new')
+        sha_old = sha256_file(self.filename, 'old')
+        sha_new = sha256_file(self.filename_tmp, 'new')
         # compare checksums
-        if shaold != shanew:
+        if sha_old != sha_new:
             # update doc file
             if os.path.exists(self.filename):
                 os.unlink(self.filename)