Manifests help to cache information which is too expensive to generate on each request. Some manifests generate maps, e.g. class names to filesystem locations. Others store aggregate information like nested configuration graphs.
By default, manifests are stored on the local filesystem through PHP's
Combined with PHP opcode caching this provides fast access.
In order to share manifests between servers, or centralise cache management,
other storage adapters are available. These can be configured by a
placed in your
ManifestCache_File: The default adapter using PHP's
var_export(), which is faster when a PHP opcode cache is installed
ManifestCache_APC: Use PHP's APC object cache
You can write your own adapters by implementing the
Traversing the Filesystem
Since manifests usually extract their information from files in the webroot, they require a powerful traversal tool: SS_FileFinder. The class provides filtering abilities for files and folders, as well as callbacks for recursive traversal. Each manifest has its own implementation, for example ManifestFileFinder, adding more domain specific filtering like including themes, or excluding tests.
PHP Class Manifest
The ClassManifest builds a manifest of all classes, interfaces and some additional items present in a directory, and caches it.
It finds the following information:
- Class and interface names and paths
- All direct and indirect descendants of a class
- All implementors of an interface
- All module configuration files
ClassInfo::subclassesFor($class): Returns a list of classes that inherit from the given class
ClassInfo::ancestry($class): Returns the passed class name along with all its parent class names
ClassInfo::implementorsOf($interfaceName): Returns all classes implementing the passed in interface
In the absence of a generic module API, it is also the primary way to identify
which modules are installed, through ClassManifest::getModules().
A module is defined as a toplevel folder in the webroot which contains
_config.php file, or a
_config/ folder. Modules can be specifically
excluded from manifests by creating a blank
_manifest_exclude file in the module folder.
By default, the finder implementation will exclude any classes stored in files within
tests/ folder, unless tests are executed.
The SS_TemplateManifest class builds a manifest of all templates present in a directory,
in both modules and themes. Templates in
tests/ folders are automatically excluded.
The chapter on template inheritance provides more details
on its operation.
The SS_ConfigManifest loads builds a manifest of configuration items, for both PHP and YAML. It also takes care of ordering and merging configuration fragments. The chapter on configuration has more details.
?flush=1 query parameter is added to a URL, a call to
flush() will be triggered
on any classes that implement the Flushable interface.
This enables developers to clear manifest caches,
for example when adding new templates or PHP classes.
Note that you need to be in dev mode
or logged-in as an administrator for flushing to take effect.