From: ara.t.howard@...
Date: 2006-08-03T23:24:10+09:00
Subject: Re: How to tell when IO::popen is finished?

On Thu, 3 Aug 2006, Daniel N wrote:

> Hi,
>
> I've just installed and had some success with the gnuplot library.
>
> I'm saving the output to a png file (plot.terminal "png") and this all works
> well, but when I try to use the file it isn't finished writing it yet and I
> get an exception.
>
> I've used
>
> Gnuplot.open(  ) do |gp|
> ....
> end
>
> while(!File.exists?("/test2.png") || File.zero?("/test2.png") )
> sleep 0.1
> end
>
> In an attempt to wait until the file is written before I try to do anything
> with it, but this seems a bit too hackish.
>
> Can I capture the Gnuplot.open into a variable and check it?  The last
> statement in the Gnuplot.open is a call to
> IO::popen( cmd, "w") { |io| yield io }
>
> but if I test the class of what is returned it is
> Gnuplot::Plot
>
> not anything to do with IO
>
> Is there a way that I can test the IO::popen to tell when it's finished?



can you show the code?  that pipe will be automatically closed once the yield
has returned.

-a
-- 
we can never obtain peace in the outer world until we make peace with
ourselves.
- h.h. the 14th dali lama