Rescue doesn't handle every error

Hello,

the example works both on Debian, Ruby 1.8.4 and Gentoo, Ruby 1.8.5

irb(main):006:0> require ‘open-uri’
=> true
irb(main):007:0> begin
irb(main):008:1* open(‘http://www.url.with.timeout.problem.com).read
irb(main):009:1> rescue
irb(main):010:1> puts ‘timeout’
irb(main):011:1> end
/usr/lib/ruby/1.8/timeout.rb:54:in rbuf_fill': execution expired (Timeout::Error) from /usr/lib/ruby/1.8/timeout.rb:56:intimeout’
from /usr/lib/ruby/1.8/timeout.rb:76:in timeout' from /usr/lib/ruby/1.8/net/protocol.rb:132:inrbuf_fill’
from /usr/lib/ruby/1.8/net/protocol.rb:116:in readuntil' from /usr/lib/ruby/1.8/net/protocol.rb:126:inreadline’
from /usr/lib/ruby/1.8/net/http.rb:2224:in read_chunked' from /usr/lib/ruby/1.8/net/http.rb:2204:inread_body_0’
from /usr/lib/ruby/1.8/net/http.rb:2170:in read_body' ... 13 levels... from /usr/lib/ruby/1.8/open-uri.rb:30:inopen’
from (irb):8:in irb_binding' from /usr/lib/ruby/1.8/irb/workspace.rb:52:inirb_binding’
from /usr/lib/ruby/1.8/irb/workspace.rb:52


I think it’s terrible bad. Rescue without explicit error type should
have deal with every error. Its purpose is to handle unexpected
errors. My production application stopped working by a bad url, but the
whole process was inside a begin-rescue-end block.

This is not the first time. I have seen same when I was dealing with
SCGI source code.

Correct me if I am wrong but I think this is a serious issue in Ruby’s
error handling and should be fixed soon.

   Mage

From: Mage [mailto:[email protected]] :

irb(main):006:0> require ‘open-uri’

=> true

irb(main):007:0> begin

irb(main):008:1* open('http://www.url.with.timeout.problem.com).read

irb(main):009:1> rescue

         rescue Exception

irb(main):010:1> puts ‘timeout’

irb(main):011:1> end

kind regards -botp

rescue without exception spec just handles RuntimeError - that’s also
documented behavior IIRC.

Regards

robert

Robert K. wrote:

rescue without exception spec just handles RuntimeError - that’s also
documented behavior IIRC.

I think it’s not documented, or I just skipped?

http://www.rubycentral.com/book/tut_exceptions.html

   Mage

Peña wrote:

         rescue Exception

Thank you, it works.

I googled for string “rescue exception”, and I found this: “‘rescue’ by
itself is like ‘rescue StandardError’, I believe (which catches
StandardError and all its subclasses)”.

If it works that way, I think, it should be documented in the Ruby book,
exception part.

Have a nice day.

   Mage

There is a timeout package in the standard library which will raise an
exception. You could use it in your code like this :

require “timeout”
require “open-uri”

begin
Timeout::timeout(60) do |timeout_length|
open('http://www.url.with.timeout.problem.com).read
end
rescue Timeout::Error
puts “timeout : 60 seconds”
end

On Fri, Feb 23, 2007, Mage wrote:

Robert K. wrote:

rescue without exception spec just handles RuntimeError - that’s also
documented behavior IIRC.

I think it’s not documented, or I just skipped?

http://www.rubycentral.com/book/tut_exceptions.html

It is:

The match is made using $!.kind_of?(parameter), and so will succeed if
the parameter has the same class as the exception or is an ancestor of
the exception. If you write a rescue clause with no parameter list,
the
parameter defaults to StandardError.

Easy to miss, though. Took me a while to find it. The explanation is
clearer (IIRC) in the second edition.

Ben

On Fri, Feb 23, 2007 at 05:34:53PM +0900, Mage wrote:

Robert K. wrote:

rescue without exception spec just handles RuntimeError - that’s also
documented behavior IIRC.

I think it’s not documented, or I just skipped?

http://www.rubycentral.com/book/tut_exceptions.html

which does say:

“If you write a rescue clause with no parameter list, the parameter
defaults
to StandardError.”

On 2/23/07, Mage [email protected] wrote:

to StandardError."

You are right, it’s my mistake.

This is a pretty common mistake, so maybe in the next edition it
should be somehow highlighted. Maybe a separate paragraph or
something…

Brian C. wrote:

You are right, it’s my mistake.

   Mage

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