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fileevent or Tk::IO with pipes

by csotzing (Sexton)
on Nov 23, 2001 at 09:48 UTC ( #127064=perlquestion: print w/replies, xml ) Need Help??

csotzing has asked for the wisdom of the Perl Monks concerning the following question:

Hello!
Simply put, I'm writing a perl/tk gui, containing a text widget and a Run button. My intent is for Run to open a pipe to the output of another perl script of mine. I want to read the output and insert it into the text widget. My other perl script (test.pl) takes a while to run, so I want to make sure that I'm using non-blocking I/O and a callback for when the pipe is readable, so that my gui doesn't freeze. So far I've tried using Tk's fileevent and the Tk::IO module, both without success. (I believe the Tk::IO's exec creates a separate thread for running my other script.) Here are some snippets from my latest attempt:
use Tk::IO; # callback for 'Run' Button sub RunCB { $fh = new Tk::IO->new(-linecommand => \&guiReadTestHandle, -childcommand => \&guiCloseTestHandle); $fh->exec("test.pl"); } # callback for when $fh is readable<BR> sub guiReadTestHandle { if (<$fh>) { $txtRunRslt->insert(end, $data); } } # callback for when $fh reaches EOF sub guiCloseTestHandle { $fh->close(); }
When I run the program and click 'Run', I get the message '-' is not recognized as an internal or external command, operable program or batch file., then the guiCloseTestHandle is called, closing the filehandle. I'm running on Win2K, with ActivePerl 5.6.1. The Tk::IO version appears to be 3.038. If anyone has any information on what I'm doing wrong, or how I can better achieve this, I would really appreciate it! Thanks, all.

Replies are listed 'Best First'.
Re: fileevent or Tk::IO with pipes
by mkmcconn (Chaplain) on Nov 23, 2001 at 10:11 UTC
    You may need to change the line to invoke perl explicitly:
    $fh->exec("perl test.pl");

    mkmcconn
    (There's almost certainly a better way to do that, if it works.)

Re: fileevent or Tk::IO with pipes
by Anonymous Monk on Nov 23, 2001 at 19:05 UTC
    Thanks for the suggestion... unfortunately, it didn't work. I've put the code for my gui, and the sample test.pl script which the gui is supposed to run on-line. If it helps, the code is located here:
    http://www.sotzing.org/stage/gui.pl
    http://www.sotzing.org/stage/test.pl
    
Re: fileevent or Tk::IO with pipes
by smackdab (Pilgrim) on Dec 09, 2001 at 09:33 UTC
    There is a good article that explains the problems you are running into. I ran into them also...

    The article is by, Stephen Lidie, he will have his advanced Perl/Tk book out this month (800 pages !!!)

    This is one of the many broken things with Win32...you have to do some other form of communication. I choose to spawn a process and use network sockets, but you could choose a pipe or shared memory or ???

    It would be nice if we could use threads or fork(), but they are also broken in Win32 ;-(

    http://www.samag.com/documents/s=1273/sam05020010/

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