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

Hi everyone! I've got exception handling subsystem which converts dies to exceptions with stack trace using Exception::Class-like lib. 

my $base_class = '...'; # base class for exceptions
my $error_class = '...'; # my error class

sub rethrow(;$) {
    my $e = @_ ? $_[0] : $@;

    die $e
        if blessed( $e ) && $e->isa( $base_class );

    die $error_class->new( $e );
}

sub try(&) {
    my $code = $_[0];

    eval {
        local $SIG{__DIE__} = \&rethrow;
        &$code();
    };

    $@;
}

[download]
And usage is: 

my $e = try {
   # some code, potentially with errors
};

[download]
Exception objects supports stringification. For most cases it works fine, but there is one case which breaks it. If I had module which dies duering loading and i'll try to require it with my try fucntion, $SIG{__DIE__} handler will be called twice. And second time it will be called with stringified exception from first time! So I lose call stack collected in first call and error location is lost. Is there any way to prevent such stringification?

Replies are listed 'Best First'.
Re: How to prevent exception stringification after error in require/use?
by thenaz (Beadle) on Aug 04, 2011 at 15:40 UTC

    Why not do:

    my $base_class = '...'; # base class for exceptions
my $error_class = '...'; # my error class

sub fixerror(;$) {
    my $e = @_ ? $_[0] : $@;

    return $e
        if blessed( $e ) && $e->isa( $base_class );

    return $error_class->new( $e );
}

sub try(&) {
    my $code = $_[0];

    eval { &$code() };

    $@ ? fixerror($@) : undef;
}

    [download]

    That way you don't have a callback that has the potential of getting called multiple times.

[reply]
[d/l]

      I take it back. You use the $SIG{__DIE__} so that you can get the stack trace at the location the exception was thrown...

[reply]

Back to Seekers of Perl Wisdom