From: Robert Klemme <shortcutter@...>
Date: 2010-02-23T04:05:14+09:00
Subject: Re: Ruby Idiom To Retry open() Upto N Times Before Giving Up

On 22.02.2010 19:53, Dan wrote:
> I write a lot of scripts that I run once or infrequently that uses open-rui Occasionally I run into a web site that times out or is unavailable for a period of time. My normal solution is to just rerun the script manually at a later time and the problem goes away. What I would like to start doing is rescuing the open() and retrying the open() after a delay. What would be the most idiomatic way to try opening a url say n times before giving up? Here is my crude code for trying twice:
> 
> begin  
>    open("http://www.example.com/foo.html")
>  rescue  
>    begin  
>       open("http://www.example.com/foo.html")
>     rescue  
>       #tried twice - giving up  
>    end  
> end  
> 
> I would like a more general approach using ruby idioms where I could specify the maximum number of attempts and delay before giving up. Thanks for your help.

You can use "retry":

irb(main):017:0> attempts = 3
=> 3
irb(main):018:0> begin
irb(main):019:1* raise "Error, attempt = #{attempts}"
irb(main):020:1> rescue => e
irb(main):021:1> puts e
irb(main):022:1> attempts -= 1
irb(main):023:1> retry if attempts > 0
irb(main):024:1> puts "giving up"
irb(main):025:1> end
Error, attempt = 3
Error, attempt = 2
Error, attempt = 1
giving up
=> nil
irb(main):026:0>

Kind regards

	robert


-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/