My application (Ruby 1.9.2) may raise different exceptions, including net-connection breaks. I rescue Exception => e, then do case/when to handle them in defferent ways, but several errors go through my cases straight to else.
rescue Exception => e p e.class case e.class when Errno::ECONNRESET p 1 when Errno::ECONNRESET,Errno::ECONNABORTED,Errno::ETIMEDOUT p 2 else p 3 end end Prints:
Errno::ECONNRESET 3 This is because of how the === operator works on the class Class
The case statement internally calls the === method on the object you are evaluating against. If you want to test for e class, you just test against e, not e.class. That's because e.class would fall into the when Class case, because, well, e.class is a Class.
rescue Exception => e case e when Errno::ECONNRESET p 1 when Errno::ECONNRESET,Errno::ECONNABORTED,Errno::ETIMEDOUT p 2 else p 3 end end Yeah, Ruby can have weird semantics sometimes
Array === Class would give true, but now I'm confused. Thanks to your comment now I can't sleep :/=== is called on the element you're comparing to. So Class === Array, String === "foobar" and /foo/ === "foobar" all return true.Well it depends upon whether you referencing the class or the constant. I have for instance had to use the following case statement to get a certain type of detection working
def fail(exception_error) exception = exception_error case exception.class when /HTTPClient::ConnectTimeoutError.new/ status = 'CONNECTION TIMEOUT' connection_status = 'DOWN' else status = 'UNKNOWN FAILURE' connection_status = 'DOWN' end But that's because I'm working with the actual Exception Class not the constant. HTTPCLient is raising an actual class object:
class TimeoutError < RuntimeError end class ConnectTimeoutError < TimeoutError end Here's a puzzling fact:
error = HTTPClient::ConnectTimeoutError.new HTTPClient::ConnectTimeoutError === error #=> true error === HTTPClient::ConnectTimeoutError #=> false Not sure what to make of that.
