From:

create_function 到底作了些什么呢？

function create_function($args, $code)
{
 static $id = 0;
 eval("function __lambda_func($args) { $code }");
 while (!runkit_function_rename('__lambda_func', "\0lambda_" . (++$id)));
 return "\0lambda_$id";
}

I'll let you contemplate on that awhile....You should be noticing the following sets of problems:

• Prone to critical abuse by user-supplied code
• Skips opcode cache optimizations

You should also be thinking about the practical issues with it:

• Code lives inside quoted strings which means awkward escaping of embedded quotes
• Encourages not using comments (evil)
• 100% blind to reflection or PHPDoc style documentation generation
• I'm sure you can come up with a couple more...