diff options
Diffstat (limited to 'activesupport')
| -rw-r--r-- | activesupport/CHANGELOG.md | 4 | ||||
| -rw-r--r-- | activesupport/lib/active_support/rescuable.rb | 142 | ||||
| -rw-r--r-- | activesupport/test/rescuable_test.rb | 21 |
3 files changed, 110 insertions, 57 deletions
diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md index 773182056b..25b8af7d34 100644 --- a/activesupport/CHANGELOG.md +++ b/activesupport/CHANGELOG.md @@ -1,2 +1,6 @@ +* Rescuable: If a handler doesn't match the exception, check for handlers + matching the exception's cause. + + *Jeremy Daer* Please check [5-0-stable](https://github.com/rails/rails/blob/5-0-stable/activesupport/CHANGELOG.md) for previous changes. diff --git a/activesupport/lib/active_support/rescuable.rb b/activesupport/lib/active_support/rescuable.rb index 73bc52b56f..2c05deee41 100644 --- a/activesupport/lib/active_support/rescuable.rb +++ b/activesupport/lib/active_support/rescuable.rb @@ -1,7 +1,6 @@ require 'active_support/concern' require 'active_support/core_ext/class/attribute' require 'active_support/core_ext/string/inflections' -require 'active_support/core_ext/array/extract_options' module ActiveSupport # Rescuable module adds support for easier exception handling. @@ -48,14 +47,12 @@ module ActiveSupport # end # # Exceptions raised inside exception handlers are not propagated up. - def rescue_from(*klasses, &block) - options = klasses.extract_options! - - unless options.has_key?(:with) + def rescue_from(*klasses, with: nil, &block) + unless with if block_given? - options[:with] = block + with = block else - raise ArgumentError, "Need a handler. Supply an options hash that has a :with key as the last argument." + raise ArgumentError, 'Need a handler. Pass the with: keyword argument or provide a block.' end end @@ -65,65 +62,104 @@ module ActiveSupport elsif klass.is_a?(String) klass else - raise ArgumentError, "#{klass} is neither an Exception nor a String" + raise ArgumentError, "#{klass.inspect} must be an Exception class or a String referencing an Exception class" end # Put the new handler at the end because the list is read in reverse. - self.rescue_handlers += [[key, options[:with]]] + self.rescue_handlers += [[key, with]] end end - end - # Tries to rescue the exception by looking up and calling a registered handler. - def rescue_with_handler(exception) - if handler = handler_for_rescue(exception) - handler.arity != 0 ? handler.call(exception) : handler.call - true # don't rely on the return value of the handler + # Matches an exception to a handler based on the exception class. + # + # If no handler matches the exception, check for a handler matching the + # (optional) exception.cause. If no handler matches the exception or its + # cause, this returns nil so you can deal with unhandled exceptions. + # Be sure to re-raise unhandled exceptions if this is what you expect. + # + # begin + # … + # rescue => exception + # rescue_with_handler(exception) || raise + # end + # + # Returns the exception if it was handled and nil if it was not. + def rescue_with_handler(exception, object: self) + if handler = handler_for_rescue(exception, object: object) + handler.call exception + exception + end end - end - def handler_for_rescue(exception) - # We go from right to left because pairs are pushed onto rescue_handlers - # as rescue_from declarations are found. - _, rescuer = self.class.rescue_handlers.reverse.detect do |klass_name, handler| - # The purpose of allowing strings in rescue_from is to support the - # declaration of handler associations for exception classes whose - # definition is yet unknown. - # - # Since this loop needs the constants it would be inconsistent to - # assume they should exist at this point. An early raised exception - # could trigger some other handler and the array could include - # precisely a string whose corresponding constant has not yet been - # seen. This is why we are tolerant to unknown constants. - # - # Note that this tolerance only matters if the exception was given as - # a string, otherwise a NameError will be raised by the interpreter - # itself when rescue_from CONSTANT is executed. - klass = self.class.const_get(klass_name) rescue nil - klass ||= (klass_name.constantize rescue nil) - klass === exception if klass + def handler_for_rescue(exception, object: self) #:nodoc: + case rescuer = find_rescue_handler(exception) + when Symbol + method = object.method(rescuer) + if method.arity == 0 + -> e { method.call } + else + method + end + when Proc + if rescuer.arity == 0 + -> e { object.instance_exec(&rescuer) } + else + -> e { object.instance_exec(e, &rescuer) } + end + end end - case rescuer - when Symbol - method(rescuer) - when Proc - if rescuer.arity == 0 - Proc.new { instance_exec(&rescuer) } - else - Proc.new { |_exception| instance_exec(_exception, &rescuer) } + private + def find_rescue_handler(exception) + if exception + # Handlers are in order of declaration but the most recently declared + # is the highest priority match, so we search for matching handlers + # in reverse. + _, handler = rescue_handlers.reverse_each.detect do |class_or_name, _| + if klass = constantize_rescue_handler_class(class_or_name) + klass === exception + end + end + + handler || find_rescue_handler(exception.cause) + end + end + + def constantize_rescue_handler_class(class_or_name) + case class_or_name + when String, Symbol + begin + # Try a lexical lookup first since we support + # + # class Super + # rescue_from 'Error', with: … + # end + # + # class Sub + # class Error < StandardError; end + # end + # + # so an Error raised in Sub will hit the 'Error' handler. + const_get class_or_name + rescue NameError + class_or_name.safe_constantize + end + else + class_or_name + end end - end end - def index_of_handler_for_rescue(exception) - handlers = self.class.rescue_handlers.reverse_each.with_index - _, index = handlers.detect do |(klass_name, _), _| - klass = self.class.const_get(klass_name) rescue nil - klass ||= (klass_name.constantize rescue nil) - klass === exception if klass - end - index + # Delegates to the class method, but uses the instance as the subject for + # rescue_from handlers (method calls, instance_exec blocks). + def rescue_with_handler(exception) + self.class.rescue_with_handler exception, object: self + end + + # Internal handler lookup. Delegates to class method. Some libraries call + # this directly, so keeping it around for compatibility. + def handler_for_rescue(exception) #:nodoc: + self.class.handler_for_rescue exception, object: self end end end diff --git a/activesupport/test/rescuable_test.rb b/activesupport/test/rescuable_test.rb index bd43ad0797..e42e6d2973 100644 --- a/activesupport/test/rescuable_test.rb +++ b/activesupport/test/rescuable_test.rb @@ -3,9 +3,6 @@ require 'abstract_unit' class WraithAttack < StandardError end -class NuclearExplosion < StandardError -end - class MadRonon < StandardError end @@ -19,6 +16,10 @@ module WeirdError end class Stargate + # Nest this so the 'NuclearExplosion' handler needs a lexical const_get + # to find it. + class NuclearExplosion < StandardError; end + attr_accessor :result include ActiveSupport::Rescuable @@ -57,6 +58,14 @@ class Stargate raise MadRonon.new("dex") end + def fall_back_to_cause + # This exception is the cause and has a handler. + ronanize + rescue + # This is the exception we'll handle that doesn't have a cause. + raise 'unhandled RuntimeError with a handleable cause' + end + def weird StandardError.new.tap do |exc| def exc.weird? @@ -74,7 +83,6 @@ class Stargate def sos_first @result = 'sos_first' end - end class CoolStargate < Stargate @@ -127,4 +135,9 @@ class RescuableTest < ActiveSupport::TestCase result = @cool_stargate.send(:rescue_handlers).collect(&:first) assert_equal expected, result end + + def test_rescue_falls_back_to_exception_cause + @stargate.dispatch :fall_back_to_cause + assert_equal 'unhandled RuntimeError with a handleable cause', @stargate.result + end end |