用PHP自动加载特征

Question

Is there any way for me to differentiate between traits and classes in my autoload function? Say I have a folder of classes and a folder of traits; it would be nice to be able to do something like...

spl_autoload_register(function($resource) {
  if ( /* $resource is class */ ) {
    include 'classes/'.$resource.'.php';
  } 
  if ( /* $resource is trait */ ) {
    include 'traits/'.$resource.'.php';
  }
});

Answer 1

The autoload callback function only receives one piece of information; the symbol name requested. There is no way to see what type of symbol it should be.

What you could do is register multiple functions in the autoload stack, one to handle classes and the other traits, using stream_resolve_include_path() or something similar, eg

spl_autoload_register(function($className) {
    $fileName = stream_resolve_include_path('classes/' . $className . '.php');
    if ($fileName !== false) {
        include $fileName;
    }
});
spl_autoload_register(function($traitName) {
    $fileName = stream_resolve_include_path('traits/' . $traitName . '.php');
    if ($fileName !== false) {
        include $fileName;
    }
});

Answer 2

There is a simple solution in the way you name your traits. Every trait in my application is named trait_(name) and it is placed in the classes folder.

For example my trait_something is placed in the classes/ folder under the filename "trait.trait_something.php".

My autoload function can pick up either the traits or the classes:

function autoloader($class) 
{
    $prefix='classes/';
    $ext='.php';
    if(substr($class,0,6) == 'trait_')include $prefix.'trait.' . $class . $ext; 
    else include $prefix.'class.' . $class . $ext;
}