# Source Resolver

You can create fake filesystems for PHPTAL templates. This lets you load templates *and macros* from any source, e.g. a database.

## Simplest way

If you don't use macros, you don't need `SourceResolver`:

``` 
   $phptal->setSource(load_source_from_anywhere());  // No source resolver necessary
```

## Implementing custom source

However, if you'd like to avoid fetching template source on every request (explained later), or would like to use macros that load additional templates, implement your own `SourceResolver`:

``` 
   class MySourceResolver implements PHPTAL_SourceResolver
   {
       function resolve($path)
       {
           if (looks_like_my_path($path)) {
               $source = load_template_from($path);
               return new PHPTAL_StringSource($source);
           }
       }
   }
```

⚠ (in PHPTAL older than 1.2.2 you need `new PHPTAL_StringSource($source, md5($source))`)

The `resolve` function should return instance of `PHPTAL_Source` (if it supports the path) or `NULL`. You can either use `PHPTAL_StringSource` class, or implement your own.

``` 
   $phptal->addSourceResolver(new MySourceResolver());
```

PHPTAL will call `resolve()` method whenever it needs to load a template set via `setTemplate()` or `metal:use-macro`. ()

### Lazy loading of templates

`PHPTAL_SourceResolver::resolve()` method could return object that doesn't load template immediately, and instead just returns information needed to load compiled template from cache:

``` 
  class MyLazyTemplate extends PHPTAL_Source
  {
      function getRealPath()
      {
          return 'fake:/my/template'; // doesn't have to be on disk
      }
      
      function getLastModifiedTime()
      {
          return mktime(0,0,0, 7,7,2010); // unix timestamp
      }
      
      function getData()
      {
          return load_the_template();
      }
  }
```

PHPTAL will call `getData()` only when `getRealPath()` or `getLastModifiedTime()` return different values.()