wml::std::lang - Multi-Lingual Support

 #use wml::std::lang

 <lang:new id=xx [short]>

 <lang:area>
 (xx) ... (yy) ...
 </lang:area>

 <lang:set-wildcard ...>

 <lang:star: ...*..>
 <lang:star:href: index.*.html|index.html>
 <lang:star:slice: index.*.html>

 <lang:xx>...</lang:xx>
 <lang:xx: ...>

 <xx>...</xx>
 <xx: ...>

 <lang:current>
 <lang:list>

This include file provides high-level multi-lingual support via Slices. Its purpose is to define the slices ``CWLANG_XX'' according to the multi-lingual selection tags.

The general intend of this slice-based approach is to use the defined slices in Pass 9 (Slice) via WMLs -o option. A typical shebang-line example for the use with a webserver's content negotiation feature is:

  #!wml -o (ALL-LANG_*)+LANG_EN:index.html.en \
        -o (ALL-LANG_*)+LANG_DE:index.html.de

Since WML 1.7.0, the CW<lang:star:slice:> tag is an alternative to this shebang-line.

Before you can use a language, you have to define the corresponding tags via CW<lang:new>. For instance when you want to use the languages english and german, use:

 <lang:new id=en>
 <lang:new id=de>

Then the following tags are defined:

 <lang:en>...</lang:en>
 <lang:de>...</lang:de>
 <lang:en: ...>
 <lang:de: ...>

i.e. for both languages a container tag and a simple tag is defined. The container tag is more readable while the simple tag is nicer for short variants. When the names CWlang:xx are still to large for you, you can use the CWshort attribute to CW<lang:new>

 <lang:new id=en short>
 <lang:new id=de short>

when then leads to the defintion of the shortcut variants:

 <en>...</en>
 <de>...</de>
 <en: ...>
 <de: ...>

Additionally you always have the CW<lang:area>...CW</lang:area> container tag available which provides an alternative way of selecting the language in its body. It automatically surrounds the data between `CW(xx)' start tags with the corresponding CWLANG_XX slice.

The following are equal:

 <lang:xx: Foo><lang:yy Bar>
 <lang:xx>Foo</lang:xx><lang:yy>Bar</lang:yy>
 <lang:area>(xx)Foo(yy)Bar</lang:area>

Because these three lines internally get expanded to

 [LANG_XX:Foo:][LANG_YY:Bar:]
 [LANG_XX:Foo:][LANG_YY:Bar:]
 [LANG_XX:Foo:][LANG_YY:Bar:]

There is one additional special tag: CW<lang:star:>. This tag expands its attribute line like the CW<lang:xx:> tags but multiple times. Actually as much as defined languages exists (CW<lang:new>!). And in each expansion the asterisks (=stars) in the data gets replaced by the language identifier.

Is is sometimes convenient to use another wildcard, e.g. when defining navigation bars. The CW<lang:set-wildcard> tag does the job. The attribute becomes the wildcard used in future substitutions. Without attribute, the default value is restored. You may specify any regular expression, and do not forget to escape special characters (the astersisk is in fact ``\\*'').

  <lang:set-wildcard "%">
  <lang:star: index.%.html>
  <lang:set-wildcard>

There is a more specialized variant named CW<lang:star:href:> which is similar to CW<lang:star:> but treats its attribute value as a URL part and tries to check if it already exists. If it doesn't exist the tag expands the value without the star or an alternative value which can be appended with ``|alt-value''.

The CW<lang:star:slice:> is another variant to help writing multi-lingual files quickly. It must come after all occurences of CW<lang:new> tags.

  <lang:star:slice: index.html.*>

The `CW%BASE' form is recognized (see wml(1)) and an empty argument is equivalent to the string `CW%BASE.*.html'. But note that the use of this tag instead of the WML shebang line prevents WMk from doing its job, because WMk can not guess output filenames in this case.

For complex multi-lingual documents, you may want to know in which language text is currently processed. This is achieved with

  <lang:current>

which always returns current language (as defined in CW<lang:new> or an empty string when outside of any language portion. The macro

  <lang:list>

prints the newline separated list of defined languages.

The following is an example of a webpage CWindex.wml with a multi-lingual header and hyperlink:

 #use wml::std::lang
 #use wml::std::href

 <lang:new id=en short>
 <lang:new id=de short>
 <lang:star:slice: index.html.*>

 <h1><en: Welcome><de: Willkommen></h1>

 <href name="The Hyperlink" url="<lang:star: index.*.html>">
 <href name="The Hyperlink" url="<lang:star:href: index2.*.html|index2.html>">

When processed via

  $ wml index.wml

The following two output files are generated (assuming that index2.html and only index2.de.html exists):

index.html.en:

  <h1>Welcome</h1>
  <a href="index.en.html">The Hyperlink</a>
  <a href="index2.html">The Hyperlink</a>

index.html.de:

  <h1>Willkommen</h1>
  <a href="index.de.html">The Hyperlink</a>
  <a href="index2.de.html">The Hyperlink</a>

 Ralf S. Engelschall
 rse@engelschall.com
 www.engelschall.com

 Denis Barbier
 barbier@engelschall.com

 Internal: P1, P2, P6, P9
 External: --

slice(1)