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--- en:public:developer:template_system:start [2012/11/20 11:27]
admin [Why is separating PHP from templates important?]
+++ en:public:developer:template_system:start [2012/11/20 11:38] (current)
admin
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 There are many benefits of separating PHP code from templates, some of which are:
-  * **SYNTAX**: Templates typically consist of semantic markup such as HTML. PHP syntax works well for application code, but quickly degenerates when mixed with HTML. ArKadia's simple <#tag> syntax is designed specifically to express presentation. ArKadia focuses your templates on presentation and less on "code". This lends to quicker template deployment and easier maintenance. ArKadia syntax requires no working knowledge of PHP, and is intuitive for programmers and non-programmers alike.
+  * **SYNTAX**: Templates typically consist of semantic markup such as HTML. PHP syntax works well for application code, but quickly degenerates when mixed with HTML. ArKadia's simple **<#tag>** syntax is designed specifically to express presentation. ArKadia focuses your templates on presentation and less on "code". This lends to quicker template deployment and easier maintenance. ArKadia syntax requires no working knowledge of PHP, and is intuitive for programmers and non-programmers alike.
-  * **FEATURES**: The template engine has many features for presentation that would otherwise need to be developed, tested and maintained in your own application code. Tags also mask the complexity of PHP statements. For example: <html><br /><br /></html><code php><?php echo strtolower(htmlspecialchars($title,ENT_QUOTES,UTF-8)); ?></code><code>{#title lowercase=1 htmlencode=1}</code>No different than PHP being an abstraction layer on top of C to simplify development, ArKadia is an abstraction layer on PHP to simplify template maintenance.
+  * **FEATURES**: The template engine has many features for presentation that would otherwise need to be developed, tested and maintained in your own application code. Tags also mask the complexity of PHP statements. For example: <html><br /><br /></html><code php><?php echo strtolower(htmlspecialchars($title,ENT_QUOTES,UTF-8)); ?></code><code><#title lowercase=1 htmlencode=1></code>No different than PHP being an abstraction layer on top of C to simplify development, ArKadia is an abstraction layer on PHP to simplify template maintenance.
   * **SANDBOXING**: When PHP is mixed with templates, there are no restrictions on what type of logic can be injected into a template. ArKadia insulates the templates from PHP, creating a controlled separation of presentation from business logic. ArKadia also has security features that can further enforce granular restrictions on templates.
-===== Templates =====
+For a syntax comparison of PHP vs ArKadia, see [[Syntax Comparison]].
-Template is simply a text file. It can generate any text-based format (HTML, XML, CSV, etc.).
-A template contains variables, which get replaced with values when the template is evaluated,
-and tags, which control the logic of the template. Below is a minimal template that illustrates a
-few basics. Each element will be explained later in this document.:
-<code html>
+===== Web designers and PHP =====
-<#doctype>
-<html>
-  <head>
-    <#meta_title>
-    <#meta_description>
-  </head>
-  <body>
-    <#frame name="topframe">
-  </body>
-</html>
-</code>
-Why use a text-based template instead of an XML-based one (like Zope's TAL)? We wanted ArKadia's template
+A common question: "Web designers have to learn a syntax anyways, why not PHP?" Of course web designers
-language to be usable for more than just XML/HTML templates. We use it for emails, JavaScript and CSV.
+can learn PHP, and they may already be familiar with it. The issue isn't their ability to learn PHP, it
-You can use the template language for any text-based format.
+is about the maintenance of PHP mixed with HTML. **<#tags>** are simpler, more intuitive, and less fragile
+than PHP statements. Templates also restrict what can be put in a template. PHP makes it too easy to add
+code into templates that doesn't belong there. You could teach designers the rules of application design,
+but this is should be unnecessary (now they are developers!) The PHP manual is intended for developers.
+Designers would only need a small fraction of this manual, and it doesn't make it easier for them to find
+what they need. ArKadia gives web designers exactly the tools they need, and gives developers fine-grained
+control over these tools.
-===== Variables =====
+===== Implementation is Important =====
-Variables look like this: <#variable>. When the template engine encounters a variable, it
+Although ArKadia gives you the tools to make a clean separation of presentation from application code,
-evaluates that variable and replaces it with the result. Variable names consist of any
+it also gives you plenty of room to bend those rules. A poor implementation (i.e. injecting PHP in
-combination of alphanumeric characters and the underscore ("_"). The dot (".") also appears
+templates) will cause more problems than the presentation separation was meant to resolve. The
-in variable sections, although that has a special meaning, as indicated below. Importantly,
+documentation does a good job of indicating what things to watch out for. Also see the [[Best
-you cannot have spaces or punctuation characters in variable names.
+Practices]] section.
-Use a dot (.) to access attributes of a variable. <#section.title> will be replaced with the
-title attribute of the section object. If you use a variable that doesn't exist, the template
-system will insert '' (the empty string) by default.
-===== Filters =====
-You can modify variables for display by using filters. Filters look like this: <#name lowercase="1">
+===== What does ArKadia look like, and how do I use it? =====
-This displays the value of the <#name> variable after being filtered through the lower filter,
-which converts text to lowercase. To give you a taste of what's available, here are some of the more
-commonly used template filters:
-=== default ===
+The [[Crash Course]] section gives a good overview how ArKadia is typically implemented in a PHP application.
-If a variable is false or empty, use given default. Otherwise, use the value of the variable
+===== How does it work? =====
-For example:
-<code html>
-<#value default="nothing">
-</code>
-=== lowercase ===
+Under the hood, ArKadia compiles copies of the templates as PHP scripts. This way you get the benefits
+of both template tag syntax and the speed of PHP. Compilation happens once when each template is
+first invoked, and then the compiled versions are used from that point forward. ArKadia takes care
+of this for you, so the template designer just edits the ArKadia templates and never has to manage
+the compiled versions. This approach keeps the templates easy to maintain, and yet keeps execution
+times extremely fast. Since the compiled versions are PHP, op-code accelerators such as APC or
+ZendCache continue to work on the compiled scripts.
-=== uppercase ===
+===== Why not use XML/XSLT syntax? =====
-=== xmlencode ===
-=== htmlencode ===
-=== httpencode ===
-=== JavascriptEncode ===
-=== rtfencode ===
+There are a couple of good reasons. First, ArKadia can be used for more than just XML/HTML based
+templates, such as generating emails, javascript, CSV, and PDF documents. Second, XML/XSLT syntax
+is even more verbose and fragile than PHP code! It is perfect for computers, but horrible for humans.
+ArKadia is about being easy to read, understand and maintain.

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