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--- en:public:developer:template_system:start [2012/11/20 11:28]
admin [Why is separating PHP from templates important?]
+++ en:public:developer:template_system:start [2012/11/20 11:38] (current)
admin
@@ Line 41: / Line 41: @@
   * **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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