The Routex.Extension.RuntimeDispatcher enables the dynamic dispatching of functions to external libraries or modules during the Plug pipeline and LiveView's handle_params. This dispatching is configured using a list of {module, function, arguments} tuples and leverages attributes from Routex.Attrs at runtime.

This is particularly useful for integrating with libraries that handle internationalization or localization, such as:

• Gettext - Set language for translations
• Fluent - Set language for translations
• Cldr - Set locale for the Cldr suite

Options

• dispatch_targets - A list of {module, function, arguments} tuples. Any argument that is a list starting with :attrs is transformed into get_in(attrs(), rest). Defaults to [{Gettext, :put_locale, [[:attrs, :runtime, :language]]}] for zero-config integration with a default Phoenix app.

Example Configuration

defmodule MyApp.RoutexBackend do
  use Routex.Backend,
    extensions: [
      Routex.Extension.Attrs,
      Routex.Extension.RuntimeDispatcher
    ],
    dispatch_targets: [
      # Dispatch Gettext locale from detected :language attribute
      {Gettext, :put_locale, [[:attrs, :runtime, :language]]},

      # Dispatch CLDR locale from detected :locale attribute
      {Cldr, :put_locale, [MyApp.Cldr, [:attrs, :runtime, :locale]]}
    ]
end

Error Handling

The extension validates all dispatch configurations during compilation to ensure the specified modules and functions exist:

• Checks if the module is loaded
• Verifies the function exists with the correct arity
• Raises a compile-time error if validation fails

Example error:

** (RuntimeError) Gettext does not provide put_locale/1.
 Please check the value of :dispatch_targets in the Routex backend module

Routex.Attrs

Requires

• none

Sets

• none

Helpers

dispatch_targets(attrs :: T.attrs) :: :ok