TP5 Code Learning Note: Loader

Auto Load Loader class A. Overview

The system calls the Loader::register () method to register for automatic loading, and after this is done, all conforming class libraries, including the third-party class library that the Composer relies on for loading, are automatically loaded.
The automatic loading of the system consists of two parts:

1. Automatic loading method of registration system \think\loader::autoload

2. Registration composer automatic loading (conforms to composer specification)

The automatic load detection sequence for a class library is:

1. Whether to define class library mappings;

2.Composer automatic load detection;

3. Whether it is a registered namespace;

4. Detect the Extended class library under the Extend_path directory;

If any of the above is detected, it is automatically loaded according to the PSR-4 naming convention.

As you can see, the way to define class library mappings is most efficient.

two. AutoLoad class

In loader::autoload ($class); Print out in $class , run as follows:

The visible $class is the class name with the namespace.

To detect namespace aliases: is there automatic loading ?

For example, a class kukiiu/uploadis defined. Give him a namespace alias orgso I can use the org/upload class to redefine the kukiiu/upload class with a org/upload class.

To define a namespace alias method:

1.\think\loader::addnamespacealias (' org ', ' kukiiu ');

check whether class library mappings are defined

Print out $map to see each element inside it as follows:

["Think\app"]=> string "F:\hwphp\study\thinkphp\library\think\App.php"

Once the mapping is defined, when the class is directly used, it is searched for the file pathname given by the definition, and then the file is loaded.

A number of commonly used class mappings are defined in mode/common.php.

To define a mapping method:

1.\think\loader::addmap (' Test ', App_path. Index\controller\test.php ');

Dump (class_exists (' Test '));

is 2.mode/common.php alias added to the map ?

Composer automatic loading

after the composer install is executed, the dependent files are created under Thinkphp/vendor.

1.TP automatic loading mechanism under parsing vendor/composer at initialization Loader::registercomposerloader ().

A) load the 'composer/autoload_namespaces.php ' file of the PSR-0 specification.

After parsing, get self:: $PREFIXESPSR 0 is:

b) Load the ' composer/autoload_psr4.php ' file of the PSR-4 specification.

After parsing, we get $PREFIXLENGTHSPSR 4 as:

$PREFIXDIRSPSR 4 is:

c) Load class map file (same as TP 's class map):' composer/autoload_classmap.php '.

d) Load the class file directly ... ' Composer/autoload_files.php '

2. when looking for a class, use Loader::findfileincomposer () to see if it is a class under composer.

It's a little complicated, look again later!

namespaces are loaded automatically

The class-map is not set, basically it is loaded by the class here. Print out the class that goes into the namespace to load automatically to see:

Resolving Namespaces

List ($name, $class) = explode (' \ \ ', $class, 2);

Take the first \ Previous value of the $class :

such as "App\index\controller\index" get $name =' app ' $class = ' index\controller\index '

if (Isset (self:: $namespace [$name])) {

Registered Namespaces

$path = self:: $namespace [$name];

} elseif (Is_dir (Extend_path. $name)) {

extending the class library namespace

$path = Extend_path. $name. DS;

} else {

return false;

}

$filename = $path. Str_replace (' \ \ ', DS, $class). EXT;

1. register the namespace:

Judging $name values are not in the registered $namespace , where the namespace and concept namespaces are not the same meaning, easy to confuse, registered here $namespace is an identity, feel called namespace prefix will be better, according to PSR-0 specification should be called ' Supplier vendor', see mode/ common.php can see that some of the default $namespace Definitions:

The $namespace printed in loader::auotload () is as follows:

So $namespace of the namespace: Span style= "Font-family:calibri" >\ $class as a prefix, this prefix to find the path it represents. such as app "F:\hwphp\study\ application\ "This path, after which if you are using a class under this path, such as a namespace of \app\myclass\test f:\hwphp\study\application\myclass\ test.php

For example: in TP frame, each module is placed in application $namespace There is a ' app ' that represents this path, so the class in the module is as long as the namespace conforms to TP \app\index\controller\index Controller, it can be converted to "F:\hwphp\study\application\index\controller\Index.php" file path.

the namespace auto-load class for TP is based on the PSR-4 standard, defined $namespace key is the namespace prefix, Value is the base path of the class. After you get the full name of the class: replace the namespace prefix with the base path, add the rest of the namespaces to it, and add the class name and suffix. unlike PSR-4 , where the namespace prefix is only one layer, eliminating the loop-judging prefix operation (list ($name, $class) = explode (' \ \ ', $class, 2);). The simple process is as follows:

To manually register a namespace (flag) method:

1. Add the following code to the application portal file:

\think\loader::addnamespace (' Kukiiu ', ' ... /extend/kukiiu/');

\think\loader::addnamespace ([

' Kukiiu ' = ' ... /extend/' Kukiiu '/',

' org ' and ' = '. /extend/org/',

]);

2. Add the configuration to the app's profile and the system will automatically register when the app executes.

' Root_namespace ' = [

' My ' = ' ... /application/extend/my/',

]

3. under mode/common.php $namespace under increase.

2. extending the Class library namespace:

Thinkphp implements the automatic registration namespace (identity) mechanism,

Put your own class library package directory into the Extend_path directory (thinkphp/extend, configurable), you can automatically register the corresponding namespace (identity),

For example: Add a mylib directory below the Thinkphp/extend directory and define a \mylib\test class ( the class file is located in the thinkphp/extend/mylib/ test.php), you can call new \mylib\test () directly;

The Extension class Library directory can be customized by defining constant Extend_path in the portal file.

As can be seen, the extension of TP class is based on the PSR-0 automatic loading standard.

  Other functions:

...

Resources:

1.HTTP://WWW.PHP-FIG.ORG/PSR. PSR Standard website.

TP5 Code Learning Note: Loader