Where's the error handling?

Post #225,518 by admin 9/19/05 6:19:26 PM Reply	Where's the error handling? For the curious... and since the other examples had it. :-) Regards, -scott anderson "Welcome to Rivendell, Mr. Anderson..."
Post #225,526 by ben_tilly 9/19/05 6:39:45 PM Reply	I wouldn't bet that it is missing I don't know that library, but a common Ruby idiom is that if you pass a block to the open method, then the called method is responsible for doing the open, loop, and necessary error checks. :-) Cheers, Ben I have come to believe that idealism without discipline is a quick road to disaster, while discipline without idealism is pointless. -- Aaron Ward (my brother)
Post #225,529 by admin 9/19/05 7:11:36 PM Reply	OK, fine... but Where is the error handling? :-) Unless the library is just eating the error (bad), then the code is ignoring the error (which is what I'm asking about). In other words, how will it know if the connection fails? Regards, -scott anderson "Welcome to Rivendell, Mr. Anderson..."
Post #225,531 by ben_tilly 9/19/05 7:25:13 PM Reply	As I said... If it follows the idiom that I've seen in other libraries, the library throws an exception that will display default error messages which will suffice for simple scripts. Cheers, Ben I have come to believe that idealism without discipline is a quick road to disaster, while discipline without idealism is pointless. -- Aaron Ward (my brother)
Post #225,532 by admin 9/19/05 7:29:04 PM Reply	Near enough to Python, then. But for purposes of this example, that's not what's being done. Regards, -scott anderson "Welcome to Rivendell, Mr. Anderson..."
Post #225,540 by JimWeirich 9/19/05 8:42:11 PM Reply	Re: Near enough to Python, then. But for purposes of this example, that's not what's being done. Actually, it is. The Perl and Python examples (1) close the socket (if it is open), (2) print a simple error message, (3) and exit with an error code. The Ruby version handles (1) within the open method automatically, and (2) and (3) in the top level exception handler provided by Ruby. If you want a more custom error message than is provided by the default error handler, or if you want a more specific error code on exit, you could do: \nbegin\n TCPSocket.open(host, port) do \|sock\|\n sock.puts(string)\n puts sock.gets\n end\nrescue Exception => ex\n puts "Error: #{ex} at #{ex.backtrace[0]}"\n exit(1)\nend\n Note that it is not necessary to explicitly close the socket, even in the presence of exceptions, when using the block form of open as coded in the examples. Error output from original code: \nrnet.rb:10:in `initialize': Connection refused - connect(2) (Errno::ECONNREFUSED)\n\tfrom rnet.rb:10:in `open'\n\tfrom rnet.rb:10\n Error output from the modified code above: \nError: Connection refused - connect(2) at rnet2.rb:11:in `initialize'\n -- -- Jim Weirich jim@weirichhouse.org [link\|http://onestepback.org\|http://onestepback.org] --------------------------------------------------------------------- "Beware of bugs in the above code; I have only proved it correct, not tried it." -- Donald Knuth (in a memo to Peter van Emde Boas)
Post #225,543 by admin 9/19/05 8:52:02 PM 9/19/05 8:53:23 PM Reply	As I said... The Python example does pretty much the same thing. If you leave off the exception handling, it closes the socket, prints a simple error message, and exits with an error code. There's nothing magical in the Ruby example. :-) So again, the examples being given here DO have a more custom error message. Which was all I was asking for. The point of the examples being good, explicit (as in, you can expect errors here, etc.) networking code suitable for showing to a beginner. So, thanks for the example. :-) Regards, -scott anderson "Welcome to Rivendell, Mr. Anderson..." Edited by admin Sept. 19, 2005, 08:53:23 PM EDT Expand All History
Post #225,544 by broomberg 9/19/05 8:57:07 PM Reply	Ahh, makes me long for the old days NOT! Doing IO programming (serial or parallel), bit twiddling the IOCTL calls for every byte, checking the handshake lines, etc. Man that sucked!

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