From: Daniel N <has.sox@...>
Date: 2006-08-03T22:29:39+09:00
Subject: How to tell when IO::popen is finished?

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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?

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