较旧的PHP版本修复

Question

Trying to dynamically load a class:

    require_once(PATH_MODULES."/{$module}/{$module}_admin.php");        
    $admin_class = $module."Admin";     
    return $admin_class::get_admin($module);

Produces this error on older versions of PHP:

Parse error: syntax error, unexpected
T_PAAMAYIM_NEKUDOTAYIM in 
/home/user/public_html/folder/path/admin/filename.php on line 91 

How can I change this code to work for older versions of PHP?

Answer 1

The problem as you probably expected, is that you cannot use dynamic class-names in PHP < 5.3. That's why the :: is unexpected after the variable.

I don't see any way to go around this. You're not allowed to do this:

 $admin_class::get_admin($module);

If this part is always the same:

$admin_class = $module."Admin";     
return $admin_class::get_admin($module);

You could (and this is a hack!) add these strings to that module with the module name filled in ofcourse. Or make a separate file for that?

So for module "yourModule" you add to the "/yourModule/yourModule_admin.php" file these lines:

$admin_class = "yourModuleAdmin";     
return yourModuleAdmin::get_admin($module);

Or add a separate file that you call yourModule_admin.olderversions.php

Not too pretty, I agree.

Answer 2

在PHP <5.3中，您可以使用call_user_func ：

return call_user_func(array($admin_class, 'get_admin'), $module);

Answer 3

Answer was pretty simple:

    $admin_class = $module."Admin";

    $oAdmin = new $admin_class;

    return $oAdmin->get_admin($module);

Answer 4

I would say, go with a factory pattern similar to what you have done in your own answer.

One way would be

static class ModuleFactory
{
  static public function get($moduleName) {
    if(file_exists($moduleName)) {
      $module= new $moduleName;
      return $module;
    }
    else {
      throw new Exception("Unkown module $moduleName");
    }
  }
}

Then you do

$fooBar = ModuleFactory::get("foobar");

I don't like string identifiers and try to avoid them when ever possible. So if you already knew all the modules you could do

static class ModuleFactory
{
  const FOO = "foo";
  const BAR = "bar";

  static public function get($moduleName) {
    if(file_exists($moduleName . '.php')) {
      $module= new $moduleName;
      return $module;
    }
    else {
      throw new Exception("Unkown module $moduleName");
    }
  }
}

And you would then be able to do

$fooBar = ModuleFactory::get(ModuleFactory::FOO);

This would reduce the chance of getting the spelling wrong.