Support per-overload [RuntimeEnabled] extended attribute

Source/bindings/scripts/code_generator_v8.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 166 matching lines @@
             code +
             '#endif // %s\n' % conditional_string)
 
 
 # [RuntimeEnabled]
 def runtime_enabled_if(code, runtime_enabled_function_name):
     if not runtime_enabled_function_name:
         return code
     # Indent if statement to level of original code
     indent = re.match(' *', code).group(0)
-    return ('%sif (%s())\n' % (indent, runtime_enabled_function_name) +
-            '    %s' % code)
+    lines = code.splitlines()
+    if len(lines) > 1:

[Nils Barth (inactive), 2014/05/27 06:33:20]

It's fine to always use a { } block, so you can eliminate this test:
CG simplicity is more important than generated code polish.

+        fmt = '%(indent)sif (%(fnname)s()) {\n    %(code)s\n%(indent)s}\n'

[Nils Barth (inactive), 2014/05/27 06:33:20]

Could you use string concatenation and split the string across lines, as in
existing code?
(It's really hard to eyeball the multi-line code.)

+    else:
+        fmt = '%(indent)sif (%(fnname)s())\n    %(code)s\n'
+    return fmt % {

[Nils Barth (inactive), 2014/05/27 06:33:20]

Could you use str.format instead of % with a dict?
(Formally this is b/c using % with a dict is dynamic,
while str.format has a static list of keywords.)

Actually, if you eliminate the if clause, I think you don't need formatting, and
can use basically the existing code, just with the split/join.

+        'indent': indent,
+        'fnname': runtime_enabled_function_name,
+        'code': '\n    '.join(lines),
+    }
 
 
 ################################################################################
 
 def main(argv):
     # If file itself executed, cache templates
     try:
         cache_dir = argv[1]
         dummy_filename = argv[2]
     except IndexError as err:
@@ skipping 10 matching lines @@
 
     # Create a dummy file as output for the build system,
     # since filenames of individual cache files are unpredictable and opaque
     # (they are hashes of the template path, which varies based on environment)
     with open(dummy_filename, 'w') as dummy_file:
         pass  # |open| creates or touches the file
 
 
 if __name__ == '__main__':
     sys.exit(main(sys.argv))