Provided by: libxml-generator-perl_1.04-1_all 
NAME
XML::Generator - Perl extension for generating XML
SYNOPSIS
use XML::Generator ':pretty';
print foo(bar({ baz => 3 }, bam()),
bar([ 'qux' => 'http://qux.com/' ],
"Hey there, world"));
# OR
require XML::Generator;
my $X = XML::Generator->new(':pretty');
print $X->foo($X->bar({ baz => 3 }, $X->bam()),
$X->bar([ 'qux' => 'http://qux.com/' ],
"Hey there, world"));
Either of the above yield:
<foo xmlns:qux="http://qux.com/">
<bar baz="3">
<bam />
</bar>
<qux:bar>Hey there, world</qux:bar>
</foo>
DESCRIPTION
In general, once you have an XML::Generator object, you then simply call methods on that
object named for each XML tag you wish to generate.
XML::Generator can also arrange for undefined subroutines in the caller's package to
generate the corresponding XML, by exporting an "AUTOLOAD" subroutine to your package.
Just supply an ':import' argument to your "use XML::Generator;" call. If you already have
an "AUTOLOAD" defined then XML::Generator can be configured to cooperate with it. See
"STACKABLE AUTOLOADs".
Say you want to generate this XML:
<person>
<name>Bob</name>
<age>34</age>
<job>Accountant</job>
</person>
Here's a snippet of code that does the job, complete with pretty printing:
use XML::Generator;
my $gen = XML::Generator->new(':pretty');
print $gen->person(
$gen->name("Bob"),
$gen->age(34),
$gen->job("Accountant")
);
The only problem with this is if you want to use a tag name that Perl's lexer won't
understand as a method name, such as "shoe-size". Fortunately, since you can store the
name of a method in a variable, there's a simple work-around:
my $shoe_size = "shoe-size";
$xml = $gen->$shoe_size("12 1/2");
Which correctly generates:
<shoe-size>12 1/2</shoe-size>
You can use a hash ref as the first parameter if the tag should include atributes.
Normally this means that the order of the attributes will be unpredictable, but if you
have the Tie::IxHash module, you can use it to get the order you want, like this:
use Tie::IxHash;
tie my %attr, 'Tie::IxHash';
%attr = (name => 'Bob',
age => 34,
job => 'Accountant',
'shoe-size' => '12 1/2');
print $gen->person(\%attr);
This produces
<person name="Bob" age="34" job="Accountant" shoe-size="12 1/2" />
An array ref can also be supplied as the first argument to indicate a namespace for the
element and the attributes.
If there is one element in the array, it is considered the URI of the default namespace,
and the tag will have an xmlns="URI" attribute added automatically. If there are two
elements, the first should be the tag prefix to use for the namespace and the second
element should be the URI. In this case, the prefix will be used for the tag and an
xmlns:PREFIX attribute will be automatically added. Prior to version 0.99, this prefix
was also automatically added to each attribute name. Now, the default behavior is to
leave the attributes alone (although you may always explicitly add a prefix to an
attribute name). If the prior behavior is desired, use the constructor option
"qualified_attributes".
If you specify more than two elements, then each pair should correspond to a tag prefix
and the corresponding URL. An xmlns:PREFIX attribute will be added for each pair, and the
prefix from the first such pair will be used as the tag's namespace. If you wish to
specify a default namespace, use '#default' for the prefix. If the default namespace is
first, then the tag will use the default namespace itself.
If you want to specify a namespace as well as attributes, you can make the second argument
a hash ref. If you do it the other way around, the array ref will simply get stringified
and included as part of the content of the tag.
Here's an example to show how the attribute and namespace parameters work:
$xml = $gen->account(
$gen->open(['transaction'], 2000),
$gen->deposit(['transaction'], { date => '1999.04.03'}, 1500)
);
This generates:
<account>
<open xmlns="transaction">2000</open>
<deposit xmlns="transaction" date="1999.04.03">1500</deposit>
</account>
Because default namespaces inherit, XML::Generator takes care to output the xmlns="URI"
attribute as few times as strictly necessary. For example,
$xml = $gen->account(
$gen->open(['transaction'], 2000),
$gen->deposit(['transaction'], { date => '1999.04.03'},
$gen->amount(['transaction'], 1500)
)
);
This generates:
<account>
<open xmlns="transaction">2000</open>
<deposit xmlns="transaction" date="1999.04.03">
<amount>1500</amount>
</deposit>
</account>
Notice how "xmlns="transaction"" was left out of the "<amount"> tag.
Here is an example that uses the two-argument form of the namespace:
$xml = $gen->widget(['wru' => 'http://www.widgets-r-us.com/xml/'],
{'id' => 123}, $gen->contents());
<wru:widget xmlns:wru="http://www.widgets-r-us.com/xml/" id="123">
<contents />
</wru:widget>
Here is an example that uses multiple namespaces. It generates the first example from the
RDF primer (http://www.w3.org/TR/rdf-primer/ <http://www.w3.org/TR/rdf-primer/>).
my $contactNS = [contact => "http://www.w3.org/2000/10/swap/pim/contact#"];
$xml = $gen->xml(
$gen->RDF([ rdf => "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
@$contactNS ],
$gen->Person($contactNS, { 'rdf:about' => "http://www.w3.org/People/EM/contact#me" },
$gen->fullName($contactNS, 'Eric Miller'),
$gen->mailbox($contactNS, {'rdf:resource' => "mailto:em@w3.org"}),
$gen->personalTitle($contactNS, 'Dr.'))));
<?xml version="1.0" standalone="yes"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:contact="http://www.w3.org/2000/10/swap/pim/contact#">
<contact:Person rdf:about="http://www.w3.org/People/EM/contact#me">
<contact:fullName>Eric Miller</contact:fullName>
<contact:mailbox rdf:resource="mailto:em@w3.org" />
<contact:personalTitle>Dr.</contact:personalTitle>
</Person>
</rdf:RDF>
CONSTRUCTOR
XML::Generator->new(':option', ...);
XML::Generator->new(option => 'value', ...);
(Both styles may be combined)
The following options are available:
:std, :standard
Equivalent to
escape => 'always',
conformance => 'strict',
:strict
Equivalent to
conformance => 'strict',
:pretty[=N]
Equivalent to
escape => 'always',
conformance => 'strict',
pretty => N # N defaults to 2
namespace
This value of this option must be an array reference containing one or two values. If the
array contains one value, it should be a URI and will be the value of an 'xmlns' attribute
in the top-level tag. If there are two or more elements, the first of each pair should be
the namespace tag prefix and the second the URI of the namespace. This will enable
behavior similar to the namespace behavior in previous versions; the tag prefix will be
applied to each tag. In addition, an xmlns:NAME="URI" attribute will be added to the top-
level tag. Prior to version 0.99, the tag prefix was also automatically added to each
attribute name, unless overridden with an explicit prefix. Now, the attribute names are
left alone, but if the prior behavior is desired, use the constructor option
"qualified_attributes".
The value of this option is used as the global default namespace. For example,
my $html = XML::Generator->new(
pretty => 2,
namespace => [HTML => "http://www.w3.org/TR/REC-html40"]);
print $html->html(
$html->body(
$html->font({ face => 'Arial' },
"Hello, there")));
would yield
<HTML:html xmlns:HTML="http://www.w3.org/TR/REC-html40">
<HTML:body>
<HTML:font face="Arial">Hello, there</HTML:font>
</HTML:body>
</HTML:html>
Here is the same example except without all the prefixes:
my $html = XML::Generator->new(
pretty => 2,
namespace => ["http://www.w3.org/TR/REC-html40"]);
print $html->html(
$html->body(
$html->font({ 'face' => 'Arial' },
"Hello, there")));
would yield
<html xmlns="http://www.w3.org/TR/REC-html40">
<body>
<font face="Arial">Hello, there</font>
</body>
</html>
qualifiedAttributes, qualified_attributes
Set this to a true value to emulate the attribute prefixing behavior of XML::Generator
prior to version 0.99. Here is an example:
my $foo = XML::Generator->new(
namespace => [foo => "http://foo.com/"],
qualifiedAttributes => 1);
print $foo->bar({baz => 3});
yields
<foo:bar xmlns:foo="http://foo.com/" foo:baz="3" />
escape
The contents and the values of each attribute have any illegal XML characters escaped if
this option is supplied. If the value is 'always', then &, < and > (and " within
attribute values) will be converted into the corresponding XML entity, although & will not
be converted if it looks like it could be part of a valid entity (but see below). If the
value is 'unescaped', then the escaping will be turned off character-by- character if the
character in question is preceded by a backslash, or for the entire string if it is
supplied as a scalar reference. So, for example,
use XML::Generator escape => 'always';
one('<'); # <one><</one>
two('\&'); # <two>\&</two>
three(\'>'); # <three>></three> (scalar refs always allowed)
four('<'); # <four><</four> (looks like an entity)
five('"'); # <five>"</five> (looks like an entity)
but
use XML::Generator escape => 'unescaped';
one('<'); # <one><</one>
two('\&'); # <two>&</two>
three(\'>'); # <three>></three> (aiee!)
four('<'); # <four>&lt;</four> (no special case for entities)
By default, high-bit data will be passed through unmodified, so that UTF-8 data can be
generated with pre-Unicode perls. If you know that your data is ASCII, use the value
'high-bit' for the escape option and bytes with the high bit set will be turned into
numeric entities. You can combine this functionality with the other escape options by
comma-separating the values:
my $a = XML::Generator->new(escape => 'always,high-bit');
print $a->foo("<\242>");
yields
<foo><¢></foo>
Because XML::Generator always uses double quotes ("") around attribute values, it does not
escape single quotes. If you want single quotes inside attribute values to be escaped,
use the value 'apos' along with 'always' or 'unescaped' for the escape option. For
example:
my $gen = XML::Generator->new(escape => 'always,apos');
print $gen->foo({'bar' => "It's all good"});
<foo bar="It's all good" />
If you actually want & to be converted to & even if it looks like it could be part of
a valid entity, use the value 'even-entities' along with 'always'. Supplying
'even-entities' to the 'unescaped' option is meaningless as entities are already escaped
with that option.
pretty
To have nice pretty printing of the output XML (great for config files that you might also
want to edit by hand), supply an integer for the number of spaces per level of indenting,
eg.
my $gen = XML::Generator->new(pretty => 2);
print $gen->foo($gen->bar('baz'),
$gen->qux({ tricky => 'no'}, 'quux'));
would yield
<foo>
<bar>baz</bar>
<qux tricky="no">quux</qux>
</foo>
You may also supply a non-numeric string as the argument to 'pretty', in which case the
indents will consist of repetitions of that string. So if you want tabbed indents, you
would use:
my $gen = XML::Generator->new(pretty => "\t");
Pretty printing does not apply to CDATA sections or Processing Instructions.
conformance
If the value of this option is 'strict', a number of syntactic checks are performed to
ensure that generated XML conforms to the formal XML specification. In addition, since
entity names beginning with 'xml' are reserved by the W3C, inclusion of this option
enables several special tag names: xmlpi, xmlcmnt, xmldecl, xmldtd, xmlcdata, and xml to
allow generation of processing instructions, comments, XML declarations, DTD's, character
data sections and "final" XML documents, respectively.
Invalid characters (http://www.w3.org/TR/xml11/#charsets) will be filtered out. To
disable this behavior, supply the 'filter_invalid_chars' option with the value 0.
See "XML CONFORMANCE" and "SPECIAL TAGS" for more information.
filterInvalidChars, filter_invalid_chars
Set this to a 1 to enable filtering of invalid characters, or to 0 to disable the
filtering. See http://www.w3.org/TR/xml11/#charsets for the set of valid characters.
allowedXMLTags, allowed_xml_tags
If you have specified 'conformance' => 'strict' but need to use tags that start with
'xml', you can supply a reference to an array containing those tags and they will be
accepted without error. It is not an error to supply this option if 'conformance' =>
'strict' is not supplied, but it will have no effect.
empty
There are 5 possible values for this option:
self - create empty tags as <tag /> (default)
compact - create empty tags as <tag/>
close - close empty tags as <tag></tag>
ignore - don't do anything (non-compliant!)
args - use count of arguments to decide between <x /> and <x></x>
Many web browsers like the 'self' form, but any one of the forms besides 'ignore' is
acceptable under the XML standard.
'ignore' is intended for subclasses that deal with HTML and other SGML subsets which allow
atomic tags. It is an error to specify both 'conformance' => 'strict' and 'empty' =>
'ignore'.
'args' will produce <x /> if there are no arguments at all, or if there is just a single
undef argument, and <x></x> otherwise.
version
Sets the default XML version for use in XML declarations. See "xmldecl" below.
encoding
Sets the default encoding for use in XML declarations.
dtd
Specify the dtd. The value should be an array reference with three values; the type, the
name and the uri.
IMPORT ARGUMENTS
use XML::Generator ':option';
use XML::Generator option => 'value';
(Both styles may be combined)
:import
Cause "use XML::Generator;" to export an "AUTOLOAD" to your package that makes undefined
subroutines generate XML tags corresponding to their name. Note that if you already have
an "AUTOLOAD" defined, it will be overwritten.
:stacked
Implies :import, but if there is already an "AUTOLOAD" defined, the overriding "AUTOLOAD"
will still give it a chance to run. See "STACKED AUTOLOADs".
ANYTHING ELSE
If you supply any other options, :import is implied and the XML::Generator object that is
created to generate tags will be constructed with those options.
XML CONFORMANCE
When the 'conformance' => 'strict' option is supplied, a number of syntactic checks are
enabled. All entity and attribute names are checked to conform to the XML specification,
which states that they must begin with either an alphabetic character or an underscore and
may then consist of any number of alphanumerics, underscores, periods or hyphens.
Alphabetic and alphanumeric are interpreted according to the current locale if 'use
locale' is in effect and according to the Unicode standard for Perl versions >= 5.6.
Furthermore, entity or attribute names are not allowed to begin with 'xml' (in any case),
although a number of special tags beginning with 'xml' are allowed (see "SPECIAL TAGS").
Note that you can also supply an explicit list of allowed tags with the 'allowed_xml_tags'
option.
Also, the filter_invalid_chars option is automatically set to 1 unless it is explicitly
set to 0.
SPECIAL TAGS
The following special tags are available when running under strict conformance (otherwise
they don't act special):
xmlpi
Processing instruction; first argument is target, remaining arguments are attribute, value
pairs. Attribute names are syntax checked, values are escaped.
xmlcmnt
Comment. Arguments are concatenated and placed inside <!-- ... --> comment delimiters.
Any occurences of '--' in the concatenated arguments are converted to '--'
xmldecl(@args)
Declaration. This can be used to specify the version, encoding, and other XML-related
declarations (i.e., anything inside the <?xml?> tag). @args can be used to control what
is output, as keyword-value pairs.
By default, the version is set to the value specified in the constructor, or to 1.0 if it
was not specified. This can be overridden by providing a 'version' key in @args. If you
do not want the version at all, explicitly provide undef as the value in @args.
By default, the encoding is set to the value specified in the constructor; if no value was
specified, the encoding will be left out altogether. Provide an 'encoding' key in @args
to override this.
If a dtd was set in the constructor, the standalone attribute of the declaration will be
set to 'no' and the doctype declaration will be appended to the XML declartion, otherwise
the standalone attribute will be set to 'yes'. This can be overridden by providing a
'standalone' key in @args. If you do not want the standalone attribute to show up,
explicitly provide undef as the value.
xmldtd
DTD <!DOCTYPE> tag creation. The format of this method is different from others. Since
DTD's are global and cannot contain namespace information, the first argument should be a
reference to an array; the elements are concatenated together to form the DTD:
print $xml->xmldtd([ 'html', 'PUBLIC', $xhtml_w3c, $xhtml_dtd ])
This would produce the following declaration:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"DTD/xhtml1-transitional.dtd">
Assuming that $xhtml_w3c and $xhtml_dtd had the correct values.
Note that you can also specify a DTD on creation using the new() method's dtd option.
xmlcdata
Character data section; arguments are concatenated and placed inside <![CDATA[ ... ]]>
character data section delimiters. Any occurences of ']]>' in the concatenated arguments
are converted to ']]>'.
xml
"Final" XML document. Must be called with one and exactly one XML::Generator-produced XML
document. Any combination of XML::Generator-produced XML comments or processing
instructions may also be supplied as arguments. Prepends an XML declaration, and re-
blesses the argument into a "final" class that can't be embedded.
CREATING A SUBCLASS
For a simpler way to implement subclass-like behavior, see "STACKABLE AUTOLOADs".
At times, you may find it desireable to subclass XML::Generator. For example, you might
want to provide a more application-specific interface to the XML generation routines
provided. Perhaps you have a custom database application and would really like to say:
my $dbxml = new XML::Generator::MyDatabaseApp;
print $dbxml->xml($dbxml->custom_tag_handler(@data));
Here, custom_tag_handler() may be a method that builds a recursive XML structure based on
the contents of @data. In fact, it may even be named for a tag you want generated, such as
authors(), whose behavior changes based on the contents (perhaps creating recursive
definitions in the case of multiple elements).
Creating a subclass of XML::Generator is actually relatively straightforward, there are
just three things you have to remember:
1. All of the useful utilities are in XML::Generator::util.
2. To construct a tag you simply have to call SUPER::tagname,
where "tagname" is the name of your tag.
3. You must fully-qualify the methods in XML::Generator::util.
So, let's assume that we want to provide a custom HTML table() method:
package XML::Generator::CustomHTML;
use base 'XML::Generator';
sub table {
my $self = shift;
# parse our args to get namespace and attribute info
my($namespace, $attr, @content) =
$self->XML::Generator::util::parse_args(@_)
# check for strict conformance
if ( $self->XML::Generator::util::config('conformance') eq 'strict' ) {
# ... special checks ...
}
# ... special formatting magic happens ...
# construct our custom tags
return $self->SUPER::table($attr, $self->tr($self->td(@content)));
}
That's pretty much all there is to it. We have to explicitly call SUPER::table() since
we're inside the class's table() method. The others can simply be called directly,
assuming that we don't have a tr() in the current package.
If you want to explicitly create a specific tag by name, or just want a faster approach
than AUTOLOAD provides, you can use the tag() method directly. So, we could replace that
last line above with:
# construct our custom tags
return $self->XML::Generator::util::tag('table', $attr, ...);
Here, we must explicitly call tag() with the tag name itself as its first argument so it
knows what to generate. These are the methods that you might find useful:
XML::Generator::util::parse_args()
This parses the argument list and returns the namespace (arrayref), attributes
(hashref), and remaining content (array), in that order.
XML::Generator::util::tag()
This does the work of generating the appropriate tag. The first argument must be the
name of the tag to generate.
XML::Generator::util::config()
This retrieves options as set via the new() method.
XML::Generator::util::escape()
This escapes any illegal XML characters.
Remember that all of these methods must be fully-qualified with the XML::Generator::util
package name. This is because AUTOLOAD is used by the main XML::Generator package to
create tags. Simply calling parse_args() will result in a set of XML tags called
<parse_args>.
Finally, remember that since you are subclassing XML::Generator, you do not need to
provide your own new() method. The one from XML::Generator is designed to allow you to
properly subclass it.
STACKABLE AUTOLOADs
As a simpler alternative to traditional subclassing, the "AUTOLOAD" that "use
XML::Generator;" exports can be configured to work with a pre-defined "AUTOLOAD" with the
':stacked' option. Simply ensure that your "AUTOLOAD" is defined before "use
XML::Generator ':stacked';" executes. The "AUTOLOAD" will get a chance to run first; the
subroutine name will be in your $AUTOLOAD as normal. Return an empty list to let the
default XML::Generator "AUTOLOAD" run or any other value to abort it. This value will be
returned as the result of the original method call.
If there is no "import" defined, XML::Generator will create one. All that this "import"
does is export AUTOLOAD, but that lets your package be used as if it were a subclass of
XML::Generator.
An example will help:
package MyGenerator;
my %entities = ( copy => '©',
nbsp => ' ', ... );
sub AUTOLOAD {
my($tag) = our $AUTOLOAD =~ /.*::(.*)/;
return $entities{$tag} if defined $entities{$tag};
return;
}
use XML::Generator qw(:pretty :stacked);
This lets someone do:
use MyGenerator;
print html(head(title("My Title", copy())));
Producing:
<html>
<head>
<title>My Title©</title>
</head>
</html>
AUTHORS
Benjamin Holzman <bholzman@earthlink.net>
Original author and maintainer
Bron Gondwana <perlcode@brong.net>
First modular version
Nathan Wiger <nate@nateware.com>
Modular rewrite to enable subclassing
SEE ALSO
The XML::Writer module
http://search.cpan.org/search?mode=module&query=XML::Writer