setter.h File Reference

Type-safe field-model writer for VLink topics. More...

#include <memory>
#include <mutex>
#include <optional>
#include <string>
#include "./impl/setter_impl.h"
#include "./node.h"
#include "./internal/setter-inl.h"

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Classes
class	vlink::Setter< ValueT, SecT >
	Type-safe field writer for the VLink field communication model. More...
class	vlink::SecuritySetter< ValueT >
	Convenience alias for Setter with message security enabled. More...

Namespaces
namespace	vlink

Detailed Description

Type-safe field-model writer for VLink topics.

Setter<ValueT, SecT> is the write side of the VLink field model. Each call to set() serialises the value and writes it to the transport as the new "latest value" for the topic. All Getter nodes on the same URL will be notified of the update.

Field Model Overview

Setter<T>                 Transport Back-end              Getter<T>
    |                          |                               |
    |-- set(value) ----------> |                               |
    |   serialize(value)       |                               |
    |                          |-- latest-value delivery ----> |
    |                          |  (overwrites previous)        |--> callback(value)
    |                          |                               |--> get() => value

Key Differences: Setter vs Publisher

Feature	Setter<T>	Publisher<T>
Transport role	kSetter	kPublisher
Value retention	Last value re-sent to late getters	No re-send to late subs
Sync callback on connect	Yes – sync() callback	No
Cross-transport use	As publisher: mark_as_publisher()	As setter: mark_as_setter()

Sync on Late Connect

When a Getter connects after the Setter has already written, the transport fires the sync() callback registered internally. The Setter re-sends its cached value so the late Getter receives the current state immediately:

Setter<int> s("shm://my_field");
s.set(42);          // Getter joins later and immediately receives 42

Usage

Setter<MyStruct> setter("dds://vehicle/gear");
setter.set(MyStruct{3, "Drive"});  // write a new field value

Template Parameters

ValueT	Value type. Must satisfy Serializer::is_supported().
SecT	Security mode; defaults to SecurityType::kWithoutSecurity.