in reply to Tk - system()

Your example is confusing. Are you trying to write the system call to the OUTFILE filehandle? Make a better example please, and explain exactly what you want to occur.

So it's hard to say from your limited code example, but you are probably running into a situation where system is blocking the Tk event loop. Tk (and all GUI's) run a thing called the event loop..... your new MainWindow; and MainLoop; statements are what start it. Once MainLoop gets called, a big loop starts running behind the scenes, doing everything you ask, on a schedule. When you put a while(1) loop in Tk, or a system call, it will hog the whole loop until it finishes (system returns).

So...... you want to avoid system calls, unless they are in a piped open or somehow forked off. Since you are writing the results to an output file ( not collecting the results internally), you can fork off the system call, and let Tk keep running it's loop. So instead of system, fork and exec. Like: 

 if(fork() == 0){ 
       exec( "$executable $title" )
         }

[download]
I don't use windows, so there may be some special syntax you need to exec your command. See how to create independent process? and Perl Tk: opening a file in its original format for more ideas.
I'm not really a human, but I play one on earth Remember How Lucky You Are

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Re^2: Tk - system()
by lil_v (Sexton) on Aug 06, 2008 at 17:25 UTC
    I am trying to create an input file from the GUI which is done by calling the OUTFILE filehandle. Then, I want to take this file and pass it to a .exe program which reads the title of the file and creates output files. This is where I call system() and try to output it to a specific directory. Before calling system, I had to specify the folder where the .exe file is if not, perl looks into the default directory and does nothing. I hope this helps. As for a better example, I wish I could give you one better but I'm having a hard time working it out.
[reply]
      Here is something else I came up with after reading the docs you wrote: 
      
my $title = "something";
#title of the input file
my $executable = "C:/Users/Desktop/file.exe";
# the .exe file where the input needs to be passed
my $output = "C:/Users/Desktop";
# folder where the generated output files need to be located
my $outfile = "C:/Users/Desktop/$title.in";
#location of the input file
    open(OUTFILE,">$outfile") or die "Can't open output file $outfile\
+n";
    print OUTFILE @array;
    close OUTFILE;

    my $msg = $mw->messageBox(-icon => "info", -type => "OK",
                              -title => 'Save', -message => "File was 
+successfully saved.");


 my @args = ("start",$executable,$title);
for (@args) {
  # Apply smart-ish double quotes
  if (/ /) { $_ = qq{"$_"}; }
};
 chdir $output;
#this command isn't working on Tk
system(@args) == 0
  or warn "Couldn't launch '$title' : $!/$?/$^E";

      [download]
      This also works fine in perl but not in Tk. I think the problem here is that it doesn't locate the $output directory. I know that you chdir does nothing if the directory is not set properly. Is there another way of specifying the directory?
[reply]
[d/l]
        Possibly the problem is you have double quotes ( which will interpolate on it's contents) around my $output = "C:/Users/Desktop";

        Try 

        chdir  'C:/Users/Desktop' ;
print pwd, "\n";  # see if it worked
#or
my $output = 'C:/Users/Desktop';

        [download]
        notice the single quotes.

        If it still gives you trouble, specify everything as full paths in single quotes, until you get it to work without the chdir. You can always do a "print pwd\n" to see where you really are. 

        my @args = ('start',  
                       'C:/Users/Desktop/file.exe' , 
                       C:/Users/Desktop/something' );

        [download]
        Once you get it to work with absolutes, work your way backwards and substitute the variables, and check pwd after any chdir attempt.
        I'm not really a human, but I play one on earth Remember How Lucky You Are
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[d/l]
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