LemonGateway.DependencyManager (lemon_gateway v0.1.0)

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Centralized dependency availability and startup manager for LemonGateway.

Engines, tools, and transport modules previously contained scattered Application.ensure_all_started/1 and Code.ensure_loaded?/1 calls. This module provides a single boundary for:

  • Ensuring OTP applications are started before use (ensure_app/1)
  • Checking module availability without starting apps (available?/1)
  • Caching availability results to avoid repeated Code.ensure_loaded? calls

Usage

case DependencyManager.ensure_app(:coding_agent) do
  :ok -> # proceed
  {:error, reason} -> # handle failure
end

if DependencyManager.available?(LemonCore.Bus) do
  LemonCore.Bus.broadcast(topic, event)
end

Summary

Functions

available?(mod)

Check whether a module is loaded and available for use.

broadcast(topic, event)

Safely emit an event to LemonCore.Bus if available.

build_event(event_type, payload, meta)

Build a LemonCore.Event.

emit_telemetry(function_name, args)

Safely emit telemetry if LemonCore.Telemetry is available.

ensure_app(app)

Ensure an OTP application and its dependencies are started.

exports?(mod, fun, arity)

Check whether a module exports a specific function.

Functions

available?(mod)

@spec available?(module()) :: boolean()

Check whether a module is loaded and available for use.

Uses Code.ensure_loaded?/1 under the hood. Suitable for optional dependencies that may not be present in all deployment configurations (e.g., LemonCore.Bus, LemonCore.Telemetry, LemonCore.Event).

broadcast(topic, event)

@spec broadcast(String.t(), term()) :: :ok

Safely emit an event to LemonCore.Bus if available.

Returns :ok regardless of whether the bus is available.

build_event(event_type, payload, meta)

@spec build_event(atom(), map(), map()) :: LemonCore.Event.t()

Build a LemonCore.Event.

This used to fall back to a bare {event_type, payload} tuple when LemonCore.Event was not loadable, from when the gateway was meant to run without core. lemon_core is a hard dependency, so that branch was unreachable — but it was a second wire shape on the bus, and consumers grew receive clauses for a tuple no one could publish. One shape now.

emit_telemetry(function_name, args)

@spec emit_telemetry(atom(), list()) :: :ok

Safely emit telemetry if LemonCore.Telemetry is available.

Accepts the telemetry function name and its arguments. Returns :ok regardless of availability.

ensure_app(app)

@spec ensure_app(atom()) :: :ok | {:error, term()}

Ensure an OTP application and its dependencies are started.

Returns :ok on success, {:error, reason} on failure. This is the unified replacement for scattered Application.ensure_all_started/1 calls in engine, tool, and transport modules.

exports?(mod, fun, arity)

@spec exports?(module(), atom(), non_neg_integer()) :: boolean()

Check whether a module exports a specific function.

Combines Code.ensure_loaded?/1 with function_exported?/3.