creating an XML string

[esharris]

I need a subroutine that takes an arbitrary string and returns that string in XML format. For example, it should change "IBM & Microsoft" into "IBM & Microsoft". The hypothetical subroutine would be simiar to CGI::escape, which returns a given string in HTML format. Does such a subroutine exist under CPAN? Though I looked around CPAN and used Google, I am having difficulty finding it. I figure there is no sense re-inventing the wheel.

Edited by Chady -- fixed &

[Joost]

I'm assuming you meant turning "IBM & Microsoft" into "IBM & Microsoft".

You will want something like XML::Writer, since strictly speaking there is no such thing as an "XML string" as you describe (mainly because the "best" encoding also depends on the character encoding of the XML file). Using an XML generator will probably save you a lot of work anyway.

[holli]

change "IBM & Microsoft" into "IBM & Microsoft"?
i assume you mean change "IBM & Microsoft" into "IBM & Microsoft", or even &.

if you know the codes of the chars you want to change, you can do something like the following:


my %ent=
(
  "&" => 38,
  "<" => 60,
  ">" => 62,
  #...
);

$string = "IBM & Microsoft > Sun\n";
print $string;

for ( keys %ent ) { $string =~ s/$_/&#$ent{$_};/g }

print $string;
#prints IBM &#38; Microsoft &#62; Sun

Another option is to put the string in question into a <![CDATA[...]]>-section.

[holli]

damn. too slow ;-)

[steves]

HTML::Entities will do it for HTML character entities. XML entities could differ. If they're a subset, HTML::Entities lets you specify which should be converted.

[PreferredUserName]

Quick &amp; dirty:

sub encode
{
    join '', map { /[\w\d ]/ ? $_ : '&#' . ord() . ';' } split //, shi
+ft;
}

[Joost]

Nasty :-)

It won't work if the argument to encode() is in LATIN-1, and your XML file is UTF-8.

update:... hmmmmmm it appears that the "most reasonable" approach would be simply

sub encode {
  my $arg = shift;
  $arg =~ s/&/&/g
  $arg =~ s/</&lt;/g;
  $arg;
}

and do the character encoding seperately using Encode, or let the filehandle figure it out.

[PreferredUserName]

Well, they don't call it "quick and dirty" because it's elegant and complete.

[steves]

Regarding XML and entities, someone may benefit from some knowledge I picked up:

• There is no need to declare numeric entities in order for them to parse okay with most (or maybe all) XML parsers. i.e., only named entities need to be declared. XML, of course, has three named entities pre-defined since they're so core: &amp;, &lt;, and &gt;.
• You can pull in all standard HTML entities by using this sort of DOCTYPE declaration:

  <!DOCTYPE doc [
  <!ENTITY % HTMLlat1 PUBLIC
          "-//W3C//ENTITIES Latin 1 for XHTML//EN"
          "http://www.w3.org/TR/xhtml1/DTD/xhtml-lat1.ent">
  %HTMLlat1;
  
  <!ENTITY % HTMLspecial PUBLIC
          "-//W3C//ENTITIES Special for XHTML//EN"
          "http://www.w3.org/TR/xhtml1/DTD/xhtml-special.ent">
  %HTMLspecial;
  
  <!ENTITY % HTMLsymbol PUBLIC
          "-//W3C//ENTITIES Symbols for XHTML//EN"
          "http://www.w3.org/TR/xhtml1/DTD/xhtml-symbol.ent">
  %HTMLsymbol;
  ]>
  

I've found the above knowledge useful since so much of the XML I create is for the purpose of transmitting web based content, which includes HTML entities.