This is a README-file for all interested in the templating system used by Koha.
It contains guidelines ans descriptions, please feel free to make comments and contributions to this file.
  
1. Introduction
  The advantage of a templating-system is the separation of code and design.
  It is much easier to read the html and get an imagination of what it will look like without having it shattered by declarations and functions.
  And it is also nicer being able to alter some functions without worrying about the webdesign.
  On the other hand templating stands in contradiction on scripting the procedural way, it forces obect-oriented programming.
  With templates Koha can be made fully skinnable, we speak of themes, and can support different languages.
  
2. How does it work
  The short version: Instead of printing html from your script you only define some template-parameters.
  You design your html-page without code in it and where you need to insert data generated by the script you can pass this data from the template-parameters via special tags.
  Indeed there is a little more to know.
  I recomend reading the documentation to the HTML::Template-module.
  You ca obtain it from http://www.perldoc.com/cpan/HTML/Template.html
  
3. How is it implemented in Koha
  Koha uses templates to handle different themes and languages.
  There is a CVS-module for the design-files: koha-tmpl.
  It contains two directories for the opac- and the intranet-templates: opac-tmpl and intranet-tmpl.
  Each of this directories reflects the available themes and their languages.
  The default theme is "default" and the default language is "en" (we use the 2letter-abbreviations, en => english, fr => french, de => german and so on).
  If you for example want to write a template for the opac part of the "custommade"-theme in polish it has to go in koha-tmpl/opac-tmpl/custommade/pl/template.tmpl.
  The template-files will not reside in your webtree, if you want to use a image you have to put this in your webtree, which is organized the same way as the templatetree (koha-html/opac-html/custommade/pl/images/image.gif).
  If you have files (either templates or files in the webspace) which are the same for all themes or languages use the "all"-directory. For example the "background.jpg"-image, which is the same for all languages within a theme should go in koha-html/(intranet|opac)-html/custommade/all/images/background.jpg).
  
4. How to use it
  Simply add an entry to the systempreferences: name=theme, value=nameoftheme.
  If you want your users be able to override your theme-settings enter name=allowthemeoverride value=customtheme1,customtheme2,... (names of themes you want to be allowed) to the preferences.
  For the language you normally don't have to enter anything, the preferences of the user's browser will be used.
  If anything is wrong you can specify a languageorder with the following entry: name=languageorder value=en,fr,de,es (or whatever comma-separated languages you want)
  If you want to specify a directory for the templates you can do so in koha.conf with 'templatedirectory=younameit'.
  
5. Rules and hints
 5.1 for the templates
  -use absolut paths, relative paths in html-tags would be relative to the script's position and relative paths in <TMPL_INCLUDE> would be relative to the template.
  -you don't have to make templates for everything in your custom-theme or language. if you omit a template in a language the template of next available language is used (languages are tried in the order of the user's browser-settings). 
   if there is no template in the specified language in a theme a different language will be chosen and NOT a different theme.
   if you omit a template in all languages the template of the default-theme will be used.
  -include comments with useful information such as the template's location, this simplifies debugging
  -use the same name for the template and the script (with different extensions of course)
 5.2 for the scripts
  -use meaningfull english (abbreviations) as parameter-names
  -if you fetch a list of data, pass it completely and let the designer decide which data to use.
  -working with arrays and loops is always better, even if you have only three similar rows.
  -don't let the script generate html and pass the output to the template
  
6. Templating stuff in Koha
  This section is to describe scripts, modules and functions within them to handle with themes, languages and other templating stuff.
  If you write something which matches this, please add a brief description here (e.g. function calls and return values).
  -function %path = pathtotemplate(%hash) in C4::Output
   Takes a hash with the following keys:
    -template: the name of the template-file (e.g. 'mytemplate.tmpl')
    -type: 'opac', 'intranet', 'none' or something you specify, decides which directory to lookup, defaults to intranet
      -'opac': /somedirs/opac-tmpl/theme/language/template.tmpl
      -'interanet': /somedirs/intranet-tmpl/theme/language/template.tmpl
      -'none': /somedirs/theme/language/template.tmpl
      -'my own words': /somedirs/my own words/theme/language/template.tmpl
      somedirs is 1. the path-parameter if specified 2. the templatedirectory in koha.conf, 3. the includes + '/templates', 4. the includes
    -theme: you can manually set a theme (e.g. 'customtheme') only if 'allowthemeoverride' in systempreferences is set
    -language: you can manually set a language (e.g. 'es')
    -path: you can manually set the path to search for templates (e.g. '/usr/koha/sometesttemplates')
    You only need to pass the last three parameters if you want to override the preferences for some reasons
   Returns:
    - $path{'path'}: the complete+absolute path of the template (e.g. '/somedirs.../opac-tmpl/customtheme/es/mytemplate.tmpl')
    - $path{'fondlanguage'}: '1' if the requested template was available in the requested language
    - $path{'fondtheme'}: '1' if the requested template was available in the requested theme
    
7. Links
  Do you have good links for the templater?
  The HTML::Template documentation: http://www.perldoc.com/cpan/HTML/Template.html
  
  
Comments to dnmeid@gmx.de
Dorian