Help:Templates: Difference between revisions

'''Templates''' are pages that can contain complex pieces of wiki markup that can be reused on other pages with relative ease.  On this help page we will go through what a template is, how to find and use them and editing and creating templates.  Finally we will have a quick look on some of the things that can be used in more advanced templates.

Most templates can be found in [[:Category:Templates]] and its subcategories.  There is also lists of some of the templates, see [[Help:List of messagebox templates]] and [[Help:List of infobox templates]].

Another way to find templates is when you find a page using templates you are interested in using.  If you open that page for editing you will on the very bottom of the page find a list of the templates used by that page and the templates those templates are using.

Most templates take arguments, called parameters.  Some templates do not.  Some parameters may be optional, some mandatory.  Mandatory parameters must always be used, while optional parameters doesn't have to.  There are also unnamed and named parameters.  Named parameters are always used in key=value pairs, like for example <tt>month={{CURRENTMONTHNAME}} {{CURRENTYEAR}}</tt>.

One thing to mention here is that unnamed parameters must be used in a certain order, though they can if not mandatory be left empty.  Take for example the following template:

If we would be to use only the last two parameters we would have to to like this below:

When you know what template you want to use, you might want to take a look at its documentation.  You will find the documentation on the template's page.  The documentation describes the purpose of the template and how to use it, as well as link to related templates.  Unfortunately not all templates are documented.

Many templates have a ''Known issues'' section in the template documentation.  Some templates have innate peculiarities that can not be fixed, but can be worked around.  One of the more common issues is that a few characters that are used to either build tables or are used within templates will break a template, those characters are a vertical stroke and some combinations of it, <tt>|</tt>, <tt>||</tt> and  <tt>|-</tt> and the equal sign <tt>=</tt>.  The usual workaround are to use the templates {{tl|!}}, {{tl|!!}}, {{tl|!-}} and {{tl|{{=}}}}.

== Editing templates ==

=== Creating new templates ===

Consider giving the template a meaningful name.  If you are mimicking a template on another wiki, using its name might be a good idea.  If the template will be used very often it might actually be a good idea to use a very short name, but proper documentation will then be even more important.  Do note that parameter names are case sensitive except for the first character.

Unless it is a very simple template it can be a good thing to start writing the documentation as this might help you figuring out the last few things in what you want the template to do and how you want it to do that, and then more or less use the documentation as reference when typing the template itself.

Do remember that you can, and should use the preview button now and then, or at least one before saving, in order to catch any errors before saving.  While the template always can be fixed if there are errors it is better to have an extra preview than an extra edit.  Do note that the template will be lost if you do not save it.

=== Editing templates ===

You might wonder what that vertical stroke and the text following, <tt><nowiki>{{{</nowiki>1'''|'''<nowiki>}}}{{{</nowiki>2'''|stranger'''<nowiki>}}}</nowiki></tt>, in ''Template:Hello'' does.  Some of you might already have guessed that they are default values.  Having at least an ''empty'' default value is a good practice, as templates otherwise will break when passed an empty parameter.  Here is what happens when the above template is used without parameters:

;Magic words:  Magic words at first look like templates except for that they mostly are all uppercase.  Some of them are for example <tt><nowiki>{{CURRENTMONTHNAME}}</nowiki></tt> and <tt><nowiki>__NOTOC__</nowiki></tt>.

;Parser functions:  Parser functions allow more or less regular programming with conditionals, switches, string formatting etc.  A good hint is that well placed empty html comments can make the code way more readable.  One of them is <tt>#if</tt>, <tt><nowiki>{{</nowiki>'''#if:''' ''string'' | ''passed if non-empty'' | ''passed if empty'' <nowiki>}}</nowiki></tt>.