initialize result variables in v8 bindings

Source/bindings/scripts/v8_types.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 102 matching lines @@
     'Promise': 'ScriptPromise',
     'ScriptValue': 'ScriptValue',
     # FIXME: Eliminate custom bindings for XPathNSResolver  http://crbug.com/345529
     'XPathNSResolver': 'RefPtrWillBeRawPtr<XPathNSResolver>',
     'boolean': 'bool',
     'unrestricted double': 'double',
     'unrestricted float': 'float',
 }
 
 
+def cpp_type_initializer(idl_type):
+    """Returns a string containing a C++ initialization statement for the
+    corresponding type.
+
+    |idl_type| argument is of type IdlType.
+    """
+
+    if (idl_type.is_numeric_type):
+        return ' = 0'
+    if idl_type.base_type == 'boolean':
+        return ' = false'
+    return ''

[Jens Widell, 2014/07/16 07:25:10]

Return None by default?

[Mostyn Bramley-Moore, 2014/07/16 07:46:56]

If I do that then we can't blindly use {{attribute.cpp_type_initializer}} in the
templates- it would have to be wrapped in a check that it's not None.

+

[Jens Widell, 2014/07/16 07:25:10]

Two blank lines between function definitions.

I'd put this after cpp_type(). Also consider putting it as a property on IdlType
(like cpp_type) to make it accessible simply as

  idl_type.cpp_type_initializer

elsewhere.

[Mostyn Bramley-Moore, 2014/07/16 07:46:56]

Done.

 def cpp_type(idl_type, extended_attributes=None, raw_type=False, used_as_argument=False, used_as_variadic_argument=False, used_in_cpp_sequence=False):
     """Returns C++ type corresponding to IDL type.
 
     |idl_type| argument is of type IdlType, while return value is a string
 
     Args:
         idl_type:
             IdlType
         raw_type:
             bool, True if idl_type's raw/primitive C++ type should be returned.
@@ skipping 608 matching lines @@
 
 def is_explicit_nullable(idl_type):
     # Nullable type that isn't implicit nullable (see above.) For such types,
     # we use Nullable<T> or similar explicit ways to represent a null value.
     return idl_type.is_nullable and not idl_type.is_implicit_nullable
 
 IdlType.is_implicit_nullable = property(is_implicit_nullable)
 IdlType.is_explicit_nullable = property(is_explicit_nullable)
 IdlUnionType.is_implicit_nullable = False
 IdlUnionType.is_explicit_nullable = property(is_explicit_nullable)