Module: Axn::Error

Included in:

Async::AdapterNotFound, Async::Adapters::Sidekiq::ConfigurationError, Async::DuplicateAdapterError, Async::MissingEnqueuesEachError, Async::UnserializableArgument, ContractViolation, DuplicateStrategyError, Axn::Extensions::Serialization::UnserializableValue, Mountable::DuplicateMountingTypeError, Mountable::MountingError, Mountable::MountingTypeNotFound, ReraiseFailed, StrategyNotFound, UnsupportedArgument

Defined in:

lib/axn/error.rb

Overview

The public-error boundary, as a MODULE rather than a base class: rescue matches a module by is_a?, so tagging a class gives callers rescue Axn::Error without touching its ancestry.

That is what makes the tag usable everywhere it needs to be. Four core errors are deliberately ArgumentErrors, and an adapter gem may need its own base to be a Faraday::Error or a Timeout::Error for its ecosystem's interop — a base class would force each of them to choose between the superclass they need and being catchable as an axn error. A module forces nothing.

Inclusion IS the boundary declaration, not a blanket sweep over everything axn raises: a class that includes this is public, documented, rescuable, and breaking to remove, and one that does not is either internal or (in the single case of Axn::Failure) deliberately excluded. That makes the boundary per-class and explicit rather than inferred from which directory a file sits in, and spec/axn/error_policy_spec.rb pins the exact partition so neither an untagged public error nor a tagged internal one can land.

Axn::Failure is the deliberate exclusion. It is a control-flow signal raised by call!, not a fault, so tagging it would make rescue Axn::Error around a call! catch the INTENDED outcome while still missing an unintended NoMethodError from the action body — a net whose partiality is the confusing part. Untagged, the three outcomes stay legible: Axn::Error means axn objected, Axn::Failure means the action deliberately failed, anything else means the body blew up. A caller who wants all three writes rescue StandardError.

A gem building on axn roots its own hierarchy here:

module Axn::Webhooks
class Error < StandardError
  include Axn::Error
end
class RetryLater < Error; end
end

The tag is inherited, so a tagged class cannot have an untagged subclass. That is deliberate: a public error family should not have secretly-internal members.