From: Forrest Chang <fkchang2000@...>
Date: 2005-08-13T07:41:11+09:00
Subject: Re: interactively processing a line at a time

"Ara.T.Howard" <Ara.T.Howard@noaa.gov> writes:

HI Ara:

   That did the trick.  Thanks.

   BTW, nice article on Grids w/RUby and SQLite

Forrest
> On Sat, 6 Aug 2005, Forrest Chang wrote:
>
>> HI All:
>>
>>        For the following code segement running on win32 ruby (1 click installer)
>>
>> sout = IO.popen( "output");
>> while( line = sout.gets)
>>  do_something_with( line)
>> end
>>
>>
>>        If for example, "output" printed out something 5 times every second,
>> then on the command line, I would see something printed out every
>> second, 5 times.  Running through the above code, I would not see
>> anything until after 5 secs, which I assume that after the program
>> exits, the output is flushed, and then it would be all 5 entries.  I
>> ran the same sort of code successfully solaris, so I expected it to
>> work on windows.
>>
>>        I did an experiment, and wrote a ruby program that printed a
>> line then flushed STDOUT, paused, repeated, etc., and it works as
>> suspected.  Since I do not have control over the actual "output"
>> program, how can I get it so that each line is flushed? sout.sync =
>> true didn't work (I imagine it only works if I write to sout)
>>
>>        Any ideas?
>
> try this - it should/might work on windoze - i assume it inherits open file
> handles from the parent.  i ran it on xp and it seemed fine:
>
>      harp:~ > ruby a.rb
>      [Fri Aug 05 20:49:51 MDT 2005, "42\n"]
>      [Fri Aug 05 20:49:56 MDT 2005, "42\n"]
>      [Fri Aug 05 20:50:01 MDT 2005, "42\n"]
>      [Fri Aug 05 20:50:06 MDT 2005, "42\n"]
>      [Fri Aug 05 20:50:11 MDT 2005, "42\n"]
>      ...
>      ...
>      ...
>
>
>      harp:~ > cat a.rb
>      require 'tempfile'
>
>      def popen_sync cmd
>        tf = Tempfile::new $PROGRAM_NAME
>        tf.puts <<-ruby_code
>          STDOUT.sync = true
>          exec STDIN.read
>        ruby_code
>        tf.close
>
>        sync_cmd = "ruby #{ tf.path }"
>        pipe = IO::popen sync_cmd, 'r+'
>        pipe.puts cmd
>        pipe.close_write
>        pipe
>      end
>
>      output = "ruby -e 'loop{ p 42; sleep 5}'"
>      sout = popen_sync output
>
>      while(line = sout.gets)
>       p [Time::now, line]
>       STDOUT.flush
>      end
>
>
> again - this will only work if exce inherits open files and there properties...
>
> hth.
>
> -a
> -- 
> ===============================================================================
> | email :: ara [dot] t [dot] howard [at] noaa [dot] gov
> | phone :: 303.497.6469
> | My religion is very simple.  My religion is kindness.
> | --Tenzin Gyatso
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