From: Kirk Haines <wyhaines@...>
Date: 2010-02-23T04:12:12+09:00
Subject: Re: Ruby Idiom To Retry open() Upto N Times Before Giving Up

On Mon, Feb 22, 2010 at 11:53 AM, Dan <dandiebolt@yahoo.com> 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
>

Use 'retry'.

This is a simple sketch of the concept:

irb(main):001:0> n = 0
=> 0
irb(main):002:0> begin
irb(main):003:1* raise "#{n} tries"
irb(main):004:1> rescue
irb(main):005:1> n += 1
irb(main):006:1> retry unless n == 3
irb(main):007:1> raise
irb(main):008:1> end
RuntimeError: 2 tries
        from (irb):3
        from :0


Kirk Haines