Create fewer local v8::TryCatch objects in generated bindings code

Source/bindings/scripts/v8_methods.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 22 matching lines @@
 Design doc: http://www.chromium.org/developers/design-documents/idl-compiler
 """
 
 from idl_types import IdlType, IdlUnionType, inherits_interface
 from v8_globals import includes
 import v8_types
 import v8_utilities
 from v8_utilities import has_extended_attribute_value
 
 
+def argument_needs_try_catch(argument):
+    return not (argument.get("is_callback_interface") or

[Nils Barth (inactive), 2014/05/07 03:02:19]

Single quotes.
Also, can't these just be usual key access?
(No need for dict.get() that I can see; if there is, it's preferred to make sure
these keys are always created, to simplify these functions.)

[Jens Widell, 2014/05/07 10:34:46]

Neither 'is_callback_interface' nor 'is_variadic_wrapper_type' was set by
constructor_argument(), and I used dict.get() for 'idl_type' too for
consistency, I guess.  But since you removed constructor_argument(), there's no
longer any need for dict.get().

[Nils Barth (inactive), 2014/05/08 00:55:13]

Got it -- I thought it might be something like that;
glad it's slicker now!

+                argument.get("idl_type") == "SerializedScriptValue" or
+                argument.get("is_variadic_wrapper_type"))
+
+
 def generate_method(interface, method):
     arguments = method.arguments
     extended_attributes = method.extended_attributes
     idl_type = method.idl_type
     is_static = method.is_static
     name = method.name
 
     idl_type.add_includes_for_type()
     this_cpp_value = cpp_value(interface, method, len(arguments))
 
@@ skipping 19 matching lines @@
         includes.add('core/dom/custom/CustomElementCallbackDispatcher.h')
 
     has_event_listener_argument = any(
         argument for argument in arguments
         if argument.idl_type.name == 'EventListener')
     is_check_security_for_frame = (
         'CheckSecurity' in interface.extended_attributes and
         'DoNotCheckSecurity' not in extended_attributes)
     is_raises_exception = 'RaisesException' in extended_attributes
 
+    generated_arguments = [generate_argument(interface, method, argument, index)
+                           for index, argument in enumerate(arguments)]
+
     return {
         'activity_logging_world_list': v8_utilities.activity_logging_world_list(method),  # [ActivityLogging]
-        'arguments': [generate_argument(interface, method, argument, index)
-                      for index, argument in enumerate(arguments)],
+        'arguments': generated_arguments,
+        'arguments_need_try_catch': any(

[Nils Barth (inactive), 2014/05/07 03:02:19]

Fix linebreaks, wrapping as follows:
        'arguments_need_try_catch': any(argument_needs_try_catch(argument)
                                        for argument in generated_arguments),

+            argument_needs_try_catch(argument) for argument in generated_arguments),
         'conditional_string': v8_utilities.conditional_string(method),
         'cpp_type': idl_type.cpp_type,
         'cpp_value': this_cpp_value,
         'deprecate_as': v8_utilities.deprecate_as(method),  # [DeprecateAs]
         'do_not_check_signature': not(is_static or
             v8_utilities.has_extended_attribute(method,
                 ['DoNotCheckSecurity', 'DoNotCheckSignature', 'NotEnumerable',
                  'ReadOnly', 'RuntimeEnabled', 'Unforgeable'])),
         'function_template': function_template(),
         'idl_type': idl_type.base_type,
@@ skipping 40 matching lines @@
         'world_suffixes': ['', 'ForMainWorld'] if 'PerWorldBindings' in extended_attributes else [''],  # [PerWorldBindings]
     }
 
 
 def generate_argument(interface, method, argument, index):
     extended_attributes = argument.extended_attributes
     idl_type = argument.idl_type
     this_cpp_value = cpp_value(interface, method, index)
     is_variadic_wrapper_type = argument.is_variadic and idl_type.is_wrapper_type
 
+    if argument.is_variadic and not is_variadic_wrapper_type:

[Nils Barth (inactive), 2014/05/07 03:02:19]

Slightly more direct:
if argument.is_variadic and not idl_typ.is_wrapper_type:

+        cpp_type = idl_type.cpp_type_args(extended_attributes=extended_attributes,

[Nils Barth (inactive), 2014/05/07 03:02:19]

Prefer single assignment:
element_cpp_type = ...

cpp_type = v8_types.cpp_template_type(vector_type, element_cpp_type)

+                                          used_in_cpp_sequence=is_variadic_wrapper_type)

[Nils Barth (inactive), 2014/05/07 03:02:19]

You can drop used_in_cpp_sequence, as it's always False, which is default.

+        vector_type = v8_types.cpp_ptr_type('Vector', 'HeapVector', idl_type.gc_type)
+        cpp_type = v8_types.cpp_template_type(vector_type, cpp_type)
+    else:
+        cpp_type = idl_type.cpp_type_args(extended_attributes=extended_attributes,

[Nils Barth (inactive), 2014/05/07 03:02:19]

Do we need to pass extended_attributes here?

(It's only needed in rare cases generally, so we've been omitting it for
simplicity and to assert that this *isn't* happening here.)

[Jens Widell, 2014/05/07 10:34:46]

Not passing it makes run-bindings-test fail with this error:
http://pastebin.com/MtuKxRL4

[Nils Barth (inactive), 2014/05/08 00:55:13]

Got it, looks like there is a use in constructors;
thanks for checking!

+                                          used_as_argument=not is_variadic_wrapper_type,
+                                          used_in_cpp_sequence=is_variadic_wrapper_type)
+
     return {
-        'cpp_type': idl_type.cpp_type_args(used_in_cpp_sequence=is_variadic_wrapper_type),
+        'cpp_type': cpp_type,
         'cpp_value': this_cpp_value,
         'enum_validation_expression': idl_type.enum_validation_expression,
         'has_default': 'Default' in extended_attributes,
         'has_event_listener_argument': any(
             argument_so_far for argument_so_far in method.arguments[:index]
             if argument_so_far.idl_type.name == 'EventListener'),
         'has_legacy_overload_string':  # [LegacyOverloadString]
             'LegacyOverloadString' in extended_attributes,
         'has_type_checking_interface':
             (has_extended_attribute_value(interface, 'TypeChecking', 'Interface') or
@@ skipping 85 matching lines @@
 
     script_wrappable = 'impl' if inherits_interface(interface_name, 'Node') else ''
     return idl_type.v8_set_return_value(cpp_value, extended_attributes, script_wrappable=script_wrappable, release=release, for_main_world=for_main_world)
 
 
 def v8_value_to_local_cpp_value(argument, index):
     extended_attributes = argument.extended_attributes
     idl_type = argument.idl_type
     name = argument.name
     if argument.is_variadic:
-        vector_type = v8_types.cpp_ptr_type('Vector', 'HeapVector', idl_type.gc_type)
-        return 'TONATIVE_VOID({vector_type}<{cpp_type}>, {name}, toNativeArguments<{cpp_type}>(info, {index}))'.format(
-            vector_type=vector_type, cpp_type=idl_type.cpp_type, name=name,
+        return 'TONATIVE_VOID_NO_DECL({name}, toNativeArguments<{cpp_type}>(info, {index}))'.format(
+            cpp_type=idl_type.cpp_type, name=name,
             index=index)
     # [Default=NullString]
     if (argument.is_optional and idl_type.name == 'String' and
         extended_attributes.get('Default') == 'NullString'):
         v8_value = 'argumentOrNull(info, %s)' % index
     else:
         v8_value = 'info[%s]' % index
     return idl_type.v8_value_to_local_cpp_value(extended_attributes, v8_value,
-                                                name, index=index)
+                                                name, index=index, declare_variable=False)
 
 
 ################################################################################
 # Auxiliary functions
 ################################################################################
 
 # [NotEnumerable]
 def property_attributes(method):
     extended_attributes = method.extended_attributes
     property_attributes_list = []
     if 'NotEnumerable' in extended_attributes:
         property_attributes_list.append('v8::DontEnum')
     if 'ReadOnly' in extended_attributes:
         property_attributes_list.append('v8::ReadOnly')
     if property_attributes_list:
         property_attributes_list.insert(0, 'v8::DontDelete')
     return property_attributes_list
 
 
 def union_arguments(idl_type):
     """Return list of ['result0Enabled', 'result0', 'result1Enabled', ...] for union types, for use in setting return value"""
     return [arg
             for i in range(len(idl_type.member_types))
             for arg in ['result%sEnabled' % i, 'result%s' % i]]
 
 IdlType.union_arguments = property(lambda self: None)
 IdlUnionType.union_arguments = property(union_arguments)