PHP，可以在同一个函数内调用函数而不指定函数名吗？

Is it possible to call function within the same function without specifying the function name - e.g by using some sort of magic keyword?

Yes. The constant __FUNCTION__ gives you a string representation of the current function. (src)

function testMe() {
  print __FUNCTION__;
}

testMe(); // outputs "testMe"

You can then of course use this to call itself:

$func = __FUNCTION__;
$func();

function someFunction($i)
{
     $method = __FUNCTION__;
     if ( $i > 0 )
     {
         return $method($i-1);
     }
     return $i;
}

simple example of recursion without knowing the functions name, will call itself for $i-times if $i is positiv.