JezK
Edit File: Error.pod
=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 $@->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<<<<<< $@-E<gt>column() >>>>>> contains the corresponding offset. Where N/A, the field is undefined. =item column $offset = $@->column(); See C<<<<<< $@-E<gt>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 2.0134 =head1 COPYRIGHT 2001-2007, AxKit.com Ltd. 2002-2006, Christian Glahn. 2006-2009, Petr Pajas. =cut =head1 LICENSE This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.