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composite_router.ex
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composite_router.ex
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defmodule Commanded.Commands.CompositeRouter do
@moduledoc """
Composite router allows you to combine multiple router modules into a single
router able to dispatch any registered command using its corresponding router.
## Example
defmodule ExampleCompositeRouter do
use Commanded.Commands.CompositeRouter
router BankAccountRouter
router MoneyTransferRouter
end
:ok = ExampleCompositeRouter.dispatch(%OpenAccount{account_number: "ACC123", initial_balance: 1_000})
"""
defmacro __using__(_opts) do
quote do
require Logger
import unquote(__MODULE__)
@registered_commands %{}
@before_compile unquote(__MODULE__)
end
end
defmacro router(router_module) do
quote location: :keep do
for command <- unquote(router_module).registered_commands() do
case Map.get(@registered_commands, command) do
nil ->
@registered_commands Map.put(@registered_commands, command, unquote(router_module))
existing_router ->
raise "duplicate registration for #{inspect command} command, registered in both #{inspect existing_router} and #{inspect unquote(router_module)}"
end
end
end
end
defmacro __before_compile__(_env) do
quote generated: true do
@doc false
def registered_commands do
Enum.map(@registered_commands, fn {command, _router} -> command end)
end
@doc false
def dispatch(command, opts \\ [])
Enum.map(@registered_commands, fn {command_module, router} ->
Module.eval_quoted(__MODULE__, quote do
@doc false
def dispatch(%unquote(command_module){} = command, opts) do
unquote(router).dispatch(command, opts)
end
end)
end)
@doc false
def dispatch(command, _opts) do
Logger.error(fn -> "attempted to dispatch an unregistered command: #{inspect command}" end)
{:error, :unregistered_command}
end
end
end
end