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InputAdapter

Overview

The InputAdapter is an abstract base class that standardises how all input sources are integrated into the system.

It forms the basis of one half of our two-way Adapter system, providing a consistent interface for input methods to issue commands to any kind of drone.

Responsibility Scope

The InputAdapter is responsible only for:

  • receiving raw input
  • converting input into Command objects
  • emitting commands to a registered handler

It is explicitly NOT responsible for:

  • drone control logic
  • simulator interaction
  • command execution
  • routing decisions

Design Goals

This abstraction ensures:

  • new input sources can be added without modifying core system logic
  • input systems can be tested independently
  • input sources can be swapped dynamically at runtime

Adding a New Input Source

To implement a new input adapter:

  1. Create a new file in: services/input/sources

  2. Subclass InputAdapter

  3. Implement required abstract methods

  4. Register the adapter in: services/input/sources/init.py

InputAdapter Class

Class Definition

Abstract base class for all input adapters.

Each subclass represents a single input channel.

Internal State

_handler

Type:

Callable[[Command], None] | None

Purpose:

Stores the function that receives emitted commands.

Initial state:

  • None until set_handler() is called

Public API

set_handler(handler: Callable[[Command], None]) -> None

Registers the callback that receives generated commands.

Parameters

  • handler: Callable that accepts a Command object

This is typically:

  • DroneAdapter.execute()
  • or a higher-level dispatcher function

Notes

  • Can accept coroutine functions, but execution scheduling must be handled by subclass if needed
  • Must be set before start() is called for normal operation

Abstract Methods

start() -> None

Begins listening for input events.

Requirements:

  • must not block execution
  • must run asynchronously or in background context
  • called once at application startup

Typical implementations:

  • keyboard event listeners
  • gesture recognition loops
  • HTTP/WebSocket input streams

Protected API

_emit(command: Command) -> None

Dispatches a constructed Command to the registered handler.

Parameters

  • command: Fully constructed Command instance

Behaviour

If no handler is registered:

  • logs warning
  • drops the command silently

If handler exists:

  • logs debug message
  • forwards command to handler

Execution Flow

  1. raw input received
  2. subclass maps input -> Command
  3. _emit(command) called
  4. handler processes command (usually DroneAdapter.execute)

Notes

  • This class is intentionally decoupled from execution systems
  • It enforces a strict one-way flow: input -> command -> handler