A C++ template library for embedded applications
MIT licensed
Designed and
maintained by
John Wellbelove
Support the development
of the ETL

Messages


Message types used for many of the framework classes.
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message_types.h

etl::message_id_t
The type used for message ids.
By default can hold a value between 0 and 255.
If ETL_MESSAGE_ID_TYPE is defined then this type will be used instead.
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etl::message_router_id_t

The type used for message router ids.
Can hold a value between 0 and 255.
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message.h

The message classes are the common communication method across all of the message capable frameworks.
They are identified by a unique id number that specialises the base class.

if ETL_POLYMORPHIC_MESSAGES is defined then messages have a public virtual destructor. The default is protected non-
virtual.
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imessage

The base class for messages.
It is this class that is passed around, usually by const reference.

const etl::message_id_t message_id;
The id of the message
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message

message<size_t ID, typename TParent = etl::imessage>

Requires an integral id as the template parameter.
Inherits from TParent, which defaults to etl::imessage.
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message_id
The id of the message.
Can be accessed by etl::imessage or etl::message instances.
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ID
The id of the message as an enum.
Can be accessed by etl::message instances.
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TParent
The class that it inherits from. It must ultimately derive from etl::imessage.
The default is etl::imessage.
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Example

enum
{
  START,
  STOP,
  SET_SPEED
};

struct MyInterface : public etl::imessage
{
  virtual void DoStuff() = 0;
};

// Start implements MyIterface
struct Start : public etl::message<START, MyInterface>
{
  void DoStuff() override
  {
    // Do stuff here. 
  }
};

struct Stop : public etl::message<STOP>
{
  bool isEmergencyStop;
};

struct SetSpeed : public etl::message<SET_SPEED>
{
  uint32_t speed;
};

void Receive(const etl::imessage& msg);