Feature #20164
openAdd Exception#deconstruct_keys
Description
It would be convenient to perform pattern matching with exception classes. So Exception#deconstruct_keys
should return a hash with :message
(original_message) as well as any other keys specific to the exception subclass.
Examples:
begin
#code
rescue => err
case err
in StandardError(message: /Permission denied/)
abort "please select a different file"
in NameError(name: :foo)
retry if require "foo_helper
else
raise
end
end
Updated by palkan (Vladimir Dementyev) 10 months ago
+1 for making exceptions pattern-matching friendly. The example above demonstrates the use case pretty well (class + message matching).
The question is what keys must be supported for each standard exception class? The plain Ruby implementation could be as follows:
class Exception
# Not sure if we need to take into account the `keys` argument
def deconstruct_keys(*) = {message:, cause:}
end
class NameError
def deconstruct_keys(*) = super.merge(name:)
end
Updated by Dan0042 (Daniel DeLorme) 10 months ago
palkan (Vladimir Dementyev) wrote in #note-1:
The question is what keys must be supported for each standard exception class?
I computed a quick list and it would look something like this.
Exception [:backtrace, :backtrace_locations, :cause, :message]
StopIteration [:result]
FrozenError [:receiver]
SignalException [:signo, :signm]
KeyError [:receiver, :key]
LoadError [:path]
LocalJumpError [:exit_value, :reason]
NameError [:name, :receiver, :local_variables]
NoMatchingPatternKeyError [:key, :matchee]
NoMethodError [:args, :private_call?]
SyntaxError [:path]
SystemCallError [:errno]
SystemExit [:status, :success?]
UncaughtThrowError [:tag, :value]
Encoding::InvalidByteSequenceError [:readagain_bytes, :source_encoding, :source_encoding_name, :incomplete_input?, :destination_encoding, :destination_encoding_name, :error_bytes]
Encoding::UndefinedConversionError [:error_char, :source_encoding, :source_encoding_name, :destination_encoding, :destination_encoding_name]
OptionParser::ParseError [:args, :reason, :additional]
Ractor::RemoteError [:ractor]
Timeout::Error [:thread]
RDoc::RI::Driver::NotFoundError [:name]
RDoc::Store::MissingFileError [:name, :file, :store]
Reline::Config::InvalidInputrc [:file, :lineno]
Gem::LoadError [:name, :requirement]
Gem::ConflictError [:target, :conflicts]
Gem::DependencyResolutionError [:conflict, :conflicting_dependencies]
Gem::FilePermissionError [:directory]
Gem::FormatException [:file_path]
Gem::GemNotInHomeException [:spec]
Gem::ImpossibleDependenciesError [:request, :build_message, :dependency, :conflicts]
Gem::MissingSpecVersionError [:specs]
Gem::RuntimeRequirementNotMetError [:suggestion]
Gem::SpecificGemNotFoundException [:name, :errors, :version]
Gem::SystemExitException [:exit_code]
Gem::UninstallError [:spec]
Gem::UnknownCommandError [:unknown_command]
Gem::UnsatisfiableDependencyError [:name, :dependency, :errors, :version]
Gem::RequestSet::Lockfile::ParseError [:column, :path, :line]
Gem::Resolver::Molinillo::CircularDependencyError [:dependencies]
Gem::Resolver::Molinillo::NoSuchDependencyError [:dependency, :required_by]
Gem::Resolver::Molinillo::VersionConflict [:specification_provider, :conflicts]
Even assuming some of those keys are not relevant, that's still a lot of #deconstruct_keys to define for various classes, so maybe a dynamic approach like below would be more feasible?
class Exception
def deconstruct_keys(*keys)
h = @diagnostics ||= {}
keys.each do |k|
unless h.key?(k)
h[a] = self.send(k) rescue nil
end
end
h
end
end