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I'm using some ruby code wrapped in a begin - rescue block but somehow it manages to still crash.
the block of code looks like this:
# Retrieve messages from server def get_messages @connection.select('INBOX') @connection.uid_search(['ALL']).each do |uid| msg = @connection.uid_fetch(uid,'RFC822').first.attr['RFC822'] begin process_message(msg) add_to_processed_folder(uid) if @processed_folder rescue handle_bogus_message(msg) end # Mark message as deleted @connection.uid_store(uid, "+FLAGS", [:Seen, :Deleted]) end end Given this code i would assume that if process_message or add_to_processed_folder could not execute then rescue would kick in and call handle_bogus_message. That being said I'm running this code in a production environment and sometimes when i "get" an email message (this is run from a rake task) it dies with a SyntaxError.
For a look at the error message check out http://pastie.org/1028479 and not that process_message that it is referring to is the same process_message above. Is there any reason why begin - rescue won't catch this exception?
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The code between “begin” and “rescue” is where a probable exception might occur. If an exception occurs, the rescue block will execute. You should try to be specific about what exception you're rescuing because it's considered a bad practice to capture all exceptions.
The method definition itself does the work of begin , so you can omit it. You can also do this with blocks. Now, there is one more way to use the rescue keyword without begin .
In Ruby, we use the rescue keyword for that. When rescuing an exception in Ruby, you can specify a specific error class that should be rescued from. Note: When using raise without specifying an exception class, Ruby will default to RuntimeError .
For each rescue clause, the raised Ruby exception is compared against each parameter and the match succeeds if the exception in the clause is the same as or a superclass of the thrown exception. If the thrown Ruby exception does not match any of the specified exception types, the else block gets executed.
rescue without a parameter just rescues exceptions that inherit from StandardError. To rescue a SyntaxError use rescue SyntaxError.
To rescue all exceptions you would use rescue Exception, but note that that's a bad idea (which is why it's not the default behavior of rescue) as explained here and here. Especially this part:
Rescuing Interrupt prevents the user from using CTRLC to exit the program.
Rescuing SignalException prevents the program from responding correctly to signals. It will be unkillable except by kill -9.
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rescue without any parameter accepts exceptions raised by StandardError class. Your error type is SyntaxError which is inherited from a different class called ScriptError. All these error classes are subclasses of Exception class. So as sepp2k suggested use rescue Exception to catch all kinds of exceptions.
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