Detailed introduction to PHP template engine Smarty_PHP tutorial

PHP template engine, Smarty, It is different from other template engines, such as FastTemplate or patTemplate. The main reason is that Smarty will convert the template into a PHP script and eliminate every time it is used. Additional code used for control and error checking will appear in the parsing process when the template is used.

This feature enables Smarty to perform well on large applications and high-traffic websites. In addition to template compilation, Smarty has many other outstanding features, which we will discuss in detail later.

First, let’s reveal the secrets of template compilation.

What does "template compilation" mean? What kind of compilation does the web page need? Doesn't compilation also need to be done for C++ and Java? Yes, but compilation will be slightly different here. Smarty parses your templates and converts them into PHP scripts instead of binary code, like you would in normal programming. In this way, when your web page is browsed, Smarty directly reads the PHP script file instead of the template itself, thus saving time to parse again.

Smarty is also smart in deciding when to compile. It will only recompile when you make actual changes to the web page, so you don't need to worry about problems with manual compilation. The advantage of this is that you don't need to know anything about PHP scripting and coding. This is all done later, so your template designer doesn't even need to know that Smarty is a "template compilation engine".

Smarty is also known for automatically caching template output.

Smarty caches the output content of the template, thus saving system overhead when retrieving data from the data source. Data sources are usually external and slow, so they are often the bottleneck of your application, as are remote data sources. Smarty caches the output of your template along with the data obtained from the data source, so you don't have to connect to the data source every time your web page is accessed. If you have a slow data source server or multiple requests to the data source, this caching feature will greatly improve the performance of your web pages.

Of course, sometimes you don't want the template output to be cached, such as a stock quote machine or you constantly modify your data source and expect these changes to be reflected immediately on the web page. These are no problem! Smarty also allows you to define what should be cached and what should not be cached. In fact, you can put cached and non-cached content on the same page, because Smarty can accurately define what can be cached (such as the navigation bar that remains unchanged forever) and what cannot be cached (such as the securities machine at the bottom of the web page). ). You can also set the validity period of cached content, so that the content of the template will only be cached for a certain period of time. This way you can find a balance between a large amount of information updated in real time and a faster website experience.

One thing that needs to be pointed out is that this caching function is completely different from Zend Cache or other PHP accelerators.

Caching tools like Zend Cache cache the bytecode generated after compiling PHP scripts, while Smarty caches the output of your template (actually a PHP script). Therefore, Smarty can work side by side with Zend Cache. Benchmark testing has found this to be a perfect solution.

As the engine creator said: Smarty's performance does improve when used with a PHP accelerator. Smarty also provides variable modification functions. You can capitalize strings, cut them, find and replace them. Variable modifiers simplify the programming process and bypass the specialized syntax that programmers often use. This gives the template designer greater control over the format of the template variables, although he first has to know which variable modifiers are available. This is a useful feature because the syntax becomes concise and people who are not programmers can use it.

Smarty also provides many built-in and custom functions in your templates.

These functions are like template APIs, except that custom functions can be modified while built-in functions cannot. These functions allow 4F60 to implement conditional output (using if statements), dynamic loop iteration (using foreach or section statements), reading config files and other functions.

Filters Smarty can categorize filters, allowing you to run filters before or after the template is compiled. Prefilters are used before your template is run, postfilters are used after the template is compiled, and output filters filter the output of the template. Why use filters? you might ask. Pre-filters can remove content you don't want and ensure that content you don't want will not be compiled. Post-filters can add additional information after the template is compiled, such as creation time. Output filters allow you to modify the template's output, such as hiding all email addresses from spam.

Config file Config file is a configuration file that can store global variables of the template. This way you can store some global variables that affect all templates in one place. A classic example is the color scheme of all templates. If the color scheme needs to be modified, the template designer only needs to change the values ​​in the configuration file. This way they don't have to modify each template one by one.

Plug-in The Smarty plug-in architecture has appeared since version 2.0, which can make Smarty more user-friendly. The pre-filters, post-filters, etc. discussed earlier are just available plug-in types. Other plug-in types include modifiers, control modules, compilers, etc. Using plugins you can make your own template functions, variable modifiers and filters. You can also use the resource plugin to change Smarty's read data format (default is flattened file).

Through the resource plug-in, you can save your template in the database and retrieve the data through a certain interface. Conclusion Combine Smarty's template compilation capabilities with PHP's inherent efficiency, and you have an absolute speed advantage. Using a well-designed plug-in architecture, Smarty also has extended functionality, including template functions and variable modifiers. The improvements in speed and functionality have not affected Smarty's affinity. In fact, Smarty is very easy to use. Smarty is also equipped for sharing documents online. You can download it from the Smarty Website.

One of the authors of Smarty, Andrei Zmievski, is also a member of the PHP development team. He will try his best to ensure that Smarty keeps up with the development of PHP. So you can rest assured: any revision of PHP will be supported by Smarty.

I hope that the introduction of the above content can be helpful to you.