Smarty is a web template system written in PHP. Smarty is primarily promoted as a tool for separation of concerns, which is a common design strategy for certain kinds of applications.Smarty generates web content by the placement of special Smarty tags within a document. These tags are processed and substituted with other code.
Tags are directives for Smarty that are enclosed by template delimiters. These directives can be variables, denoted by a dollar sign ($), functions, logical or loop statements. Smarty allows PHP programmers to define custom functions that can be accessed using Smarty tags.
Smarty is intended to simplify compartmentalization, allowing the presentation of a web page to change separately from the back-end. Ideally, this eases the costs and efforts associated with software maintenance. Under successful application of this development strategy, designers are shielded from the back-end coding, and PHP programmers are shielded from the presentation coding.
Smarty compiles your templates into PHP scripts, eliminating the overhead incurred in parsing the templates every time they're accessed. This makes Smarty very scalable for large applications and high-traffic Websites .
Smarty parses your templates and creates PHP scripts from them (instead of binaries, as in general programming). Then, when your Web page is viewed, Smarty reads from these PHP scripts instead of pulling the templates themselves, which saves the work of having to parse your templates again. Smarty is smart about when to compile, too: it only re-compiles your templates when you make changes to them, so you don't have to worry about manually compiling the templates (this is similar to JSP, if you're aware of how it works).
Smarty also features built-in caching of your template outputs. Smarty caches the output of the template contents, saving the overhead expense involved in retrieving your data from a data source. This data source would usually be external and slow, and is often the bottleneck in your application, like a remote database. Smarty caches the output of your template with this data from your data source, and saves you from having to connect to the database every time your Web page is accessed. If you have a slow-responding database server or are making multiple queries to your database, this caching feature would greatly improve the performance and responsiveness of your Web pages.
Smarty also provides variable modifiers, which, as the name implies, allow you to modify the contents of a variable. Variable modifiers give your template designers the ability to modify your template variables without being confused by those funny characters we programmers so like to use. This sanitized method of 'programming' gives your template designers greater control over the formatting of your template variable, though they would need to know the variable modifiers available to them. It is still, without doubt, a useful feature, as the syntax is kept simple and is accessible to even non-programmers.
Smarty provides built-in and custom functions for use in your templates. These functions are like the API of Smarty templates, except that custom functions can be modified but not built-in functions. Functions allow you to do things like program conditional output (using if statements), perform iteration with dynamic loops (using foreach or section), load config files, cycle though a set of values (useful for alternating table row colors), keep a counter (useful for numbering list data), and much more.
It's particularly of use to those of us generating Web pages with content from databases are the looping functions (section and foreach), which you can use to loop over and display a result set.
