BB.Message behaviour (bb v0.2.1)

Message envelope and behaviour for payload types.

Messages in BB are wrapped in a standard envelope containing timing, coordinate frame, and payload data.

Usage

Use the use BB.Message macro to define a payload type:

defmodule MyPayload do
  defstruct [:value]

  use BB.Message,
    schema: [
      value: [type: :float, required: true]
    ]
end

{:ok, msg} = MyPayload.new(:base_link, value: 1.5)

The macro will:

Validate struct fields match schema keys at compile time
Implement the schema/0 callback
Generate a new/2 helper function

Note: defstruct must be defined before use BB.Message.

Summary

Types

t()

Callbacks

schema()

Returns a compiled Spark.Options schema for this payload type

Functions

new(payload_module, frame_id, attrs)

Create a new message with validated payload.

new!(payload_module, frame_id, attrs)

Like new/3 but raises on validation error.

schema(message)

Get the payload schema from a message.

Types

t()

@type t() :: %BB.Message{frame_id: atom(), payload: struct(), timestamp: integer()}

Callbacks

schema()

@callback schema() :: Spark.Options.t()

Returns a compiled Spark.Options schema for this payload type

Functions

new(payload_module, frame_id, attrs)

@spec new(module(), atom(), keyword()) :: {:ok, t()} | {:error, term()}

Create a new message with validated payload.

Validates the attributes against the payload module's schema, then wraps the resulting struct in a message envelope with a fresh timestamp.

Examples

alias BB.Message.Geometry.Pose
alias BB.Message.{Vec3, Quaternion}

{:ok, msg} = BB.Message.new(Pose, :end_effector, [
  position: Vec3.new(1.0, 0.0, 0.5),
  orientation: Quaternion.identity()
])

new!(payload_module, frame_id, attrs)

@spec new!(module(), atom(), keyword()) :: t()

Like new/3 but raises on validation error.

Examples

msg = BB.Message.new!(Pose, :end_effector, [
  position: Vec3.new(1.0, 0.0, 0.5),
  orientation: Quaternion.identity()
])

schema(message)

@spec schema(t()) :: Spark.Options.t()

Get the payload schema from a message.

Examples

BB.Message.schema(msg)  #=> %Spark.Options{...}