Struct ExtensionDescriptor 

pub struct ExtensionDescriptor { /* private fields */ }

A linked extension descriptor.

An extension is a field declared outside the message it belongs to — extend Foo { optional int32 bar = 100; } adds field 100 to Foo from anywhere that can see Foo. Structurally it is a FieldDescriptor plus the identity of the message it extends and the fully-qualified name it is registered under.

The contained field() descriptor is what the ReflectMessage accessors take — msg.get(ext.field()) reads an extension exactly like a declared field. This mirrors protobuf-go, where ExtensionDescriptor is a FieldDescriptor and the reflective accessors don’t distinguish.

Constructed only by DescriptorPool; not constructible by downstream crates.

Implementations

impl ExtensionDescriptor

pub fn field(&self) -> &FieldDescriptor

The field this extension adds to the extendee.

Pass this to ReflectMessage accessors: msg.get(ext.field()), msg.has(ext.field()), msg.set(ext.field(), value).

The returned descriptor’s json_name() is not the JSON key for this extension — extensions serialize as the bracketed full_name() ("[pkg.ext_name]"), not as a camelCase field name. A reflection-driven serializer must special-case extension fields.

pub fn full_name(&self) -> &str

Fully-qualified registration name (the JSON "[...]" key without the brackets).

pub fn json_key(&self) -> &str

The JSON object key for this extension: the bracketed full_name(), e.g. "[pkg.ext_name]".

pub fn extendee(&self) -> MessageIndex

The message this extension extends.

Trait Implementations

impl AsRef<FieldDescriptor> for ExtensionDescriptor

fn as_ref(&self) -> &FieldDescriptor

Equivalent to field(), for generic code that accepts “anything that is a field descriptor”.

impl Clone for ExtensionDescriptor

fn clone(&self) -> ExtensionDescriptor

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ExtensionDescriptor

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.