NaSe77 has asked for the wisdom of the Perl Monks concerning the following question:

Felow Monks,

I search a way to redirect the STDERR of my programm into a nice Tk Window . I'm sure there is a easy way to do it, but if i tried it with using a fileevent 

$main->fileevent(\*STDERR,'readable',[\&tackle_err]);

sub tackle_err{
        $_ = <STDERR>;
        my $error_window = $main->Toplevel();
        $error_window -> Label (
                -text => $_
        )->pack;
        $error_window -> Button (
                -text => "OK",
                -command => sub {$error_window->destroy}
        )->pack;
}

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i got as error 
Use of uninitialized value in <HANDLE> at /usr/lib/perl5/site_perl/5.6
+.1/i386-linux/Tk/Event/IO.pm line 46.

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thanks for your wisdom ...

NaSe

Replies are listed 'Best First'.
Re: redirecting STDERR
by ozone (Friar) on May 16, 2002 at 10:06 UTC
    Your sub should start more like this: 
    sub tackle_err{
        my $file_handle = shift;
        $_ = <$file_handle>;

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    You weren't reading from the filehandle you passed in. Not sure why you got an undef back from reading the handle directly though. <thumbsuck>Might be TK opening the filehandle directly, so you no longer have direct access ... </thumbsuck>
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[d/l]
[select]
      it works now thanx (i use now Tk::ErrorDialog and sub tackle_err with the errormessage as argument): 
      use Tk::ErrorDialog;

sub tackle_err{
        my $label_text = shift;
        my $error_window = $main->Toplevel(
                                        -title => "Error!!"
                                );
        $error_window -> Label (
                                -text => $label_text
                        )->pack(
                                -side=>"top", 
                                -expand=>1,
                                -padx=>100, 
                                -anchor=>'n'
                        );
        $error_window -> Button (
                                -text => "OK",
                                -command => sub {$error_window->destro
+y}
                        )->pack;
}

      [download]

      NaSe

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[d/l]
Re: redirecting STDERR
by particle (Vicar) on May 16, 2002 at 10:58 UTC
    ozone gave a good piece of advice. i'd like to add that there's no reason to pass \*STDERR when *STDERR will do. typeglobs like being passed around as they are, and it's very efficient to boot.

    ~Particle *accelerates*

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[d/l]
[select]
      remark :

      it doesn't work if i don't use a ref there: 

      Not a GLOB reference at /usr/lib/perl5/site_perl/5.6.1/i386-linux/Tk/E
+vent/IO.pm line 107.

      [download]

      NaSe

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[d/l]
        hrumph. silly me, i should have read the doc for that.

        ~Particle *accelerates*

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