From: Dylan Evans <dylan.star@...>
Date: 2009-03-19T11:36:40+09:00
Subject: Re: Wrapping applications in Ruby

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I won't go into details but you should look into pipes in this case. By
creating a process  which does the work your wrapper code can just wait on
the pipe.


On Thu, Mar 19, 2009 at 10:13 AM, Jp Hastings-spital
<jphastings@gmail.com>wrote:

> Variants on this theme have been posted time and again, but I can't find
> a solution for this specific problem:
>
> Say I have a program I need to use that performs a task for a given
> amount of time then finishes, all the while providing a 'percent
> complete' style output on STDOUT. eg:
>
> ./counting.rb
> [RUBY]
> #!/usr/bin/env ruby
> n = 0
>
> while n <= 10
>  $stdout.puts "Completed: #{n*10}%"
>  n = n + 1
> end
> [/RUBY]
>
> Now, I'd like to build a ruby script that will call this script, wait
> until completion and then continue with its tasks BUT all the while
> updating a variable with the percentage complete. eg:
>
> ./script.rb
> [RUBY]
> def updatePercentage(pc)
>  p "The percentage is now #{pc}"
> end
>
> Thread.new {
>  # -- Problem area
>
>  # Attempt 1
>  `./counting.rb`
>  # This will wait until after counting.rb is complete before
>  # "All Done!" is printed, but I can't get to its stdout stream
>  # before the program has finished running
>
>  # Attempt 2
>  Open3.popen3('./counting.rb') { |stdin, stdout, stderr|
>    p stdout.readpartial(1)
>
>    # With a view to doing something like:
>    updatePercentage(stdout.readline.gsub(/^.*([0-9]+)%.*$/,"$1"))
>  }
>  # This doesn't work, counting.rb never begins executing
>  # (tested by adding a line: open('output.txt','w') {|file| file.puts
> "Percentage: #{n*10}%" }
>  # to counting.rb and watching the file externally)
>
>  p "All done!"
> }
>
> p "Irrelevant things"
> sleep
> [/RUBY]
>
> Any ideas anyone? Essentially I'm looking for ways to wrap C programs
> into ruby.
>
> Cheers, JP
> --
> Posted via http://www.ruby-forum.com/.
>
>


-- 
The UNIX system has a command, nice ... in order to be nice to the other
users. Nobody ever uses it." - Andrew S. Tanenbaum

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