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=head1 NAME
XML::LibXML::Error - Structured Errors
=head1 SYNOPSIS
eval { ... };
if (ref($@)) {
# handle a structured error (XML::LibXML::Error object)
} elsif ($@) {
# error, but not an XML::LibXML::Error object
} else {
# no error
}
$XML::LibXML::Error::WARNINGS=1;
$message = $@->as_string();
print $@->dump();
$error_domain = $@->domain();
$error_code = $@->code();
$error_message = $@->message();
$error_level = $@->level();
$filename = $@->file();
$line = $@->line();
$nodename = $@->nodename();
$error_str1 = $@->str1();
$error_str2 = $@->str2();
$error_str3 = $@->str3();
$error_num1 = $@->num1();
$error_num2 = $@->num2();
$string = $@->context();
$offset = $@->column();
$previous_error = $@->_prev();
=head1 DESCRIPTION
The XML::LibXML::Error class is a tiny frontend to I<<<<<< libxml2 >>>>>>'s structured error support. If XML::LibXML is compiled with structured error
support, all errors reported by libxml2 are transformed to XML::LibXML::Error
objects. These objects automatically serialize to the corresponding error
messages when printed or used in a string operation, but as objects, can also
be used to get a detailed and structured information about the error that
occurred.
Unlike most other XML::LibXML objects, XML::LibXML::Error doesn't wrap an
underlying I<<<<<< libxml2 >>>>>> structure directly, but rather transforms it to a blessed Perl hash reference
containing the individual fields of the structured error information as hash
key-value pairs. Individual items (fields) of a structured error can either be
obtained directly as $@->{field}, or using autoloaded methods such as as
$@->field() (where field is the field name). XML::LibXML::Error objects have
the following fields: domain, code, level, file, line, nodename, message, str1,
str2, str3, num1, num2, and _prev (some of them may be undefined).
=over 4
=item $XML::LibXML::Error::WARNINGS
$XML::LibXML::Error::WARNINGS=1;
Traditionally, XML::LibXML was suppressing parser warnings by setting libxml2's
global variable xmlGetWarningsDefaultValue to 0. Since 1.70 we do not change
libxml2's global variables anymore; for backward compatibility, XML::LibXML
suppresses warnings. This variable can be set to 1 to enable reporting of these
warnings via Perl C<<<<<< warn >>>>>> and to 2 to report hem via C<<<<<< die >>>>>>.
=item as_string
$message = $@->as_string();
This function serializes an XML::LibXML::Error object to a string containing
the full error message close to the message produced by I<<<<<< libxml2 >>>>>> default error handlers and tools like xmllint. This method is also used to
overload "" operator on XML::LibXML::Error, so it is automatically called
whenever XML::LibXML::Error object is treated as a string (e.g. in print $@).
=item dump
print $@->dump();
This function serializes an XML::LibXML::Error to a string displaying all
fields of the error structure individually on separate lines of the form 'name'
=> 'value'.
=item domain
$error_domain = $@->domain();
Returns string containing information about what part of the library raised the
error. Can be one of: "parser", "tree", "namespace", "validity", "HTML parser",
"memory", "output", "I/O", "ftp", "http", "XInclude", "XPath", "xpointer",
"regexp", "Schemas datatype", "Schemas parser", "Schemas validity", "Relax-NG
parser", "Relax-NG validity", "Catalog", "C14N", "XSLT", "validity".
=item code
$error_code = $@->code();
Returns the actual libxml2 error code. The XML::LibXML::ErrNo module defines
constants for individual error codes. Currently libxml2 uses over 480 different
error codes.
=item message
$error_message = $@->message();
Returns a human-readable informative error message.
=item level
$error_level = $@->level();
Returns an integer value describing how consequent is the error.
XML::LibXML::Error defines the following constants:
=over 4
=item *
XML_ERR_NONE = 0
=item *
XML_ERR_WARNING = 1 : A simple warning.
=item *
XML_ERR_ERROR = 2 : A recoverable error.
=item *
XML_ERR_FATAL = 3 : A fatal error.
=back
=item file
$filename = $@->file();
Returns the filename of the file being processed while the error occurred.
=item line
$line = $@->line();
The line number, if available.
=item nodename
$nodename = $@->nodename();
Name of the node where error occurred, if available. When this field is
non-empty, libxml2 actually returned a physical pointer to the specified node.
Due to memory management issues, it is very difficult to implement a way to
expose the pointer to the Perl level as a XML::LibXML::Node. For this reason,
XML::LibXML::Error currently only exposes the name the node.
=item str1
$error_str1 = $@->str1();
Error specific. Extra string information.
=item str2
$error_str2 = $@->str2();
Error specific. Extra string information.
=item str3
$error_str3 = $@->str3();
Error specific. Extra string information.
=item num1
$error_num1 = $@->num1();
Error specific. Extra numeric information.
=item num2
$error_num2 = $@->num2();
In recent libxml2 versions, this value contains a column number of the error or
0 if N/A.
=item context
$string = $@->context();
For parsing errors, this field contains about 80 characters of the XML near the
place where the error occurred. The field C<<<<<< $@->column() >>>>>> contains the corresponding offset. Where N/A, the field is undefined.
=item column
$offset = $@->column();
See C<<<<<< $@->column() >>>>>> above.
=item _prev
$previous_error = $@->_prev();
This field can possibly hold a reference to another XML::LibXML::Error object
representing an error which occurred just before this error.
=back
=head1 AUTHORS
Matt Sergeant,
Christian Glahn,
Petr Pajas
=head1 VERSION
2.0018
=head1 COPYRIGHT
2001-2007, AxKit.com Ltd.
2002-2006, Christian Glahn.
2006-2009, Petr Pajas.
=cut