errors/script_errors_past_bare_rescue.rb

tests/_examples/errors/script_errors_past_bare_rescue.rb in the metorex repository.

# A bare `rescue` and the `rescue` modifier catch StandardError and what
# descends from it. LoadError and NotImplementedError are ScriptErrors, so
# they go past both to a handler that names them.
def attempt
  begin
    yield
  rescue => error
    "bare rescue caught #{error.class}"
  end
rescue ScriptError => error
  "ScriptError handler caught #{error.class}"
end

p(attempt { require("no_such_feature_for_this_example") })
p(attempt { raise(NotImplementedError, "not here") })
p(attempt { raise(ArgumentError, "bad") })
p(attempt { Integer("x") })
p(LoadError.ancestors.include?(StandardError))
p(NotImplementedError.ancestors.include?(ScriptError))

value = begin
  (require("no_such_feature_for_this_example") rescue :modifier_caught)
rescue LoadError
  :passed_the_modifier
end
p(value)
p((raise(ArgumentError) rescue :modifier_caught))

Output:

"ScriptError handler caught LoadError"
"ScriptError handler caught NotImplementedError"
"bare rescue caught ArgumentError"
"bare rescue caught ArgumentError"
false
true
:passed_the_modifier
:modifier_caught