Question

What s wrong with this eval statement in Perl? I m trying to check that the XML is valid by catching any exceptions thrown from the parsing of the file with XML::LibXML:

use XML::LibXML;
my $parser = XML::LibXML->new();   #creates a new libXML object.

    eval { 
    my $tree = $parser->parse_file($file) # parses the file contents into the new libXML object.
    };
    warn() if $@;

Answer 1

Easy, $tree doesn t persist past the eval {}. Braces in perl as a general rule always provide a new scope. And warn requires you to provide its arguments $@.

my $tree;
eval { 
    # parses the file contents into the new libXML object.
    $tree = $parser->parse_file($file)
};
warn $@ if $@;

Answer 2

You re declaring a $tree inside the braces, which means it doesn t exist past the closing brace. Try this:

use XML::LibXML;
my $parser = XML::LibXML->new();

my $tree;
eval { 
    $tree = $parser->parse_file($file) # parses the file contents into the new libXML object.
};
warn("Error encountered: $@") if $@;

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