Descriptor-class: Class "Descriptor"

Description

full descriptive information about a protocol buffer message type. This is a thin wrapper around the C++ class Descriptor

Arguments

Objects from the Class

Objects are usually created by calls to the P function.

Slots

pointer:: external pointer holding a Descriptor object
type:: full name of the corresponding message type

Methods

as.character: signature(x = "Descriptor"): returns the debug string of the descriptor. This is retrieved by a call to the DebugString method of the Descriptor object.
toString: signature(x = "Descriptor"): same as as.character
$: signature(x = "Descriptor"): retrieves a descriptor for a member of the message type. This can either be another "Descriptor" instance describing a nested type, or a EnumDescriptor object describing an enum type, or a FieldDescriptor object describing a field of the message
new: signature(Class = "Descriptor"): creates a prototype message (Message) of this descriptor
show: signature(object = "Descriptor"): simple information
containing_type: signature(object = "Descriptor") : returns a descriptor of the message type that contains this message descriptor, or NULL if this is a top-level message type.
field_count: signature(object = "Descriptor") : The number of fields of this message type.
nested_type_count: signature(object = "Descriptor") : The number of nested types of this message type.
enum_type_count: signature(object = "Descriptor") : The number of enum types of this message type.
field: signature(object = "Descriptor") : extract a field descriptor from a descriptor. Exactly one argument of index, number or name has to be used. If index is used, the field descriptor is retrieved by position, using the field method of the google::protobuf::Descriptor C++ class. If number is used, the field descriptor is retrieved using the tag number, with the FindFieldByNumber C++ method. If name is used, the field descriptor is retrieved by name using the FindFieldByName
nested_type: signature(object = "Descriptor") : extracts a message type descriptor that is nested in this descriptor. Exactly one argument of index of name has to be used. If index is used, the nested type will be retrieved using its position with the nested_type method of the google::protobuf::Descriptor C++ class. If name is used, the nested type will be retrieved using its name, with the FindNestedTypeByName C++ method
enum_type: signature(object = "Descriptor") : extracts an enum type descriptor that is contained in this descriptor. Exactly one argument of index of name has to be used. If index is used, the enum type will be retrieved using its position with the enum_type method of the google::protobuf::Descriptor C++ class. If name is used, the enum type will be retrieved using its name, with the FindEnumTypeByName C++ method
[[: signature(x = "Descriptor"): extracts a field identified by its name or declared tag number
names: signature(x = "Descriptor") : extracts names of this descriptor
length: signature(x = "Descriptor") : extracts length of this descriptor

Author

Romain Francois <francoisromain@free.fr>

Examples

Run this code

if (FALSE) {
# example proto file supplied with this package
proto.file <- system.file( "proto", "addressbook.proto", package = "RProtoBuf" )
# reading a proto file and creating the descriptor
Person <- P( "tutorial.Person", file = proto.file )
}
Person <- P( "tutorial.Person" ) 

# enum type
Person$PhoneType

# nested type
Person$PhoneNumber

# field
Person$email

# use this descriptor to create a message
new( Person )

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