in reply to Bug in eval in pre-5.14

When I add control over die() and exit() I can make the code stop right at the first die on any version. Tested on 5.8 and 5.22.

#!/usr/bin/perl
use warnings;
use strict;

BEGIN {
# control eval's bypass of die
$SIG{__DIE__} = \&Splacker;
}

print $], "\n";

{   package My::Obj;

    sub new {
        my $class = shift;
        bless {@_}, $class
    }

    sub DESTROY {
        my $self = shift;
        eval { 1 } if ! $self->{finished};
    }
}

my $o1 = 'My::Obj'->new(finished => 1);
undef $o1;


# Exception overlooked.
eval {
    my $o2 = 'My::Obj'->new;
    die "Exception!";
};
if ($@) {
    warn "Caught with \$\@: $@";
}


# Exception details lost.
eval {
    my $o2 = 'My::Obj'->new;
    die "Exception!";
1 } or do {
    warn "Caught with or: $@";
};


# Same as above.
use Try::Tiny;

try {
    my $o3 = 'My::Obj'->new;
    die "Exception!";
} catch {
    warn "Caught with Try::Tiny: $_";
};

sub Splacker {
my $error = shift;
print $error;
CORE::exit(1);
}

[download]

Output:
5.008008
Exception! at C:\xampp\cgi-bin\Test\tester.pl line 32.

[download]


Update: And if you comment out CORE::exit(1); the output is.
Caught with or:  at C:\xampp\cgi-bin\Test\tester.pl line 44.
Caught with Try::Tiny:  at C:\xampp\cgi-bin\Test\tester.pl line 55.
5.008008
Exception! at C:\xampp\cgi-bin\Test\tester.pl line 32.
Exception! at C:\xampp\cgi-bin\Test\tester.pl line 42.
Exception! at C:\xampp\cgi-bin\Test\tester.pl line 53.

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Update 2: Forgot about STDERR. If used in print like so.
sub Splacker {
my $error = shift;
print STDERR $error;
}

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The Output is...
Exception! at C:\xampp\cgi-bin\Test\tester.pl line 32.
Exception! at C:\xampp\cgi-bin\Test\tester.pl line 42.
Caught with or:  at C:\xampp\cgi-bin\Test\tester.pl line 44.
Exception! at C:\xampp\cgi-bin\Test\tester.pl line 53.
Caught with Try::Tiny:  at C:\xampp\cgi-bin\Test\tester.pl line 55.
5.008008

[download]

Replies are listed 'Best First'.
Re^2: Bug in eval in pre-5.14
by choroba (Cardinal) on Aug 13, 2016 at 17:59 UTC
    The point of try/catch is not to stop on the first error (or print it), but to process it and decide to rethrow or continue.

    ($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

    [download]
[reply]
[d/l]

      With a little tweaking of the code it can be done. I was playing around with it so there is more code in Splacker then needed. 

      #!/usr/bin/perl
use warnings;
use strict;

BEGIN {
# control eval's bypass of die
$SIG{__DIE__} = \&Splacker;
}

my $error_log = '';

print $], "\n";

{   package My::Obj;

    sub new {
        my $class = shift;
        bless {@_}, $class
    }

    sub DESTROY {
        my $self = shift;
        eval { 1 } if ! $self->{finished};
    }
}

my $o1 = 'My::Obj'->new(finished => 1);
undef $o1;

# Exception Found.
eval {
    my $o2 = 'My::Obj'->new;
    die "Exception 0!";
};
# And Caught
if (Splacker()) {
    warn 'Caught with Splacker: '.Splacker();
}

# Give back die control if you want...
$SIG{__DIE__} = \&CORE::die;
# Exception overlooked.
eval {
    my $o2 = 'My::Obj'->new;
    die "Exception 1!";
};
if ($@) {
    warn "Caught with \$\@: $@";
}

# Exception details lost.
eval {
    my $o2 = 'My::Obj'->new;
    die "Exception 2!";
1 } or do {
    warn "Caught with or: $@";
};


# Same as above.
use Try::Tiny;

try {
    my $o3 = 'My::Obj'->new;
    die "Exception 3!";
} catch {
    warn "Caught with Try::Tiny: $_";
};

sub Splacker {
my $error = shift || '';

 if ($error eq 'DIE') {
  print STDERR $error.' '.$error_log;
  CORE::exit(1);
 }
  elsif ($error) {
  $error_log = $error;
 # print STDERR $error;
 }
  else {
  return $error_log;
  }
}

      [download]
      Output: 
      Caught with Splacker: Exception 0! at C:\xampp\cgi-bin\Test\tester.pl 
+line 33.
Caught with or:  at C:\xampp\cgi-bin\Test\tester.pl line 56.
Caught with Try::Tiny:  at C:\xampp\cgi-bin\Test\tester.pl line 67.
5.008008

      [download]

[reply]
[d/l]
[select]
        OK, and now change {1} in the object's destructor to { die 'inside' } - all other cases still catch the Exception #, but Splacker catches the inner one.

        ($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

        [download]
[reply]
[d/l]
[select]

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