Class: ElasticGraph::SchemaArtifacts::RuntimeMetadata::ExtensionLoader

Inherits:
Object
  • Object
show all
Defined in:
lib/elastic_graph/schema_artifacts/runtime_metadata/extension_loader.rb

Overview

Responsible for loading extensions. This loader requires an interface definition (a class or module with empty method definitions that just serves to define what loaded extensions must implement). That allows us to verify the extension implements the interface correctly at load time, rather than deferring exceptions to when the extension is later used.

Note, however, that this does not guarantee no runtime exceptions from the use of the extension: the extension may return invalid return values, or throw exceptions when called. But this verifies the interface to the extent that we can.

Instance Method Summary collapse

Constructor Details

#initialize(interface_def) ⇒ ExtensionLoader

Returns a new instance of ExtensionLoader.



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# File 'lib/elastic_graph/schema_artifacts/runtime_metadata/extension_loader.rb', line 25

def initialize(interface_def)
  @interface_def = interface_def
  @loaded_by_name = {}
end

Instance Method Details

#load(constant_name, from:, config:) ⇒ Object

Loads the extension using the provided constant name, after requiring the ‘from` path. Memoizes the result.



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# File 'lib/elastic_graph/schema_artifacts/runtime_metadata/extension_loader.rb', line 32

def load(constant_name, from:, config:)
  (@loaded_by_name[constant_name] ||= load_extension(constant_name, from)).tap do |extension|
    if extension.require_path != from
      raise InvalidExtensionError, "Extension `#{constant_name}` cannot be loaded from `#{from}`, " \
        "since it has already been loaded from `#{extension.require_path}`."
    end
  end.with(extension_config: config)
end