无法访问包含文件中的全局变量

Question

I am having an unexpected issue with scope. The include documentation (also applies to require_once) says the required file should have access to all variable at the line it was required.

For some reason I am not able to access a class instantiated with global scope inside a function that was required in.

Would anyone know why? I am obviously missing something.

I got it working through a reference to $GLOBALS[], but I still want to know why it is not working.

UPDATE:
The error I am getting is:

Fatal error: Call to a member function isAdmin() on a non-object in <path>.php on <line>

Code:

$newClass = new myClass();

require_once("path to my file");

----- inside required file -----
function someFunction() {
     $newClass->someMethod(); // gives fatal error. (see above).
}

Answer 1

Functions define a new scope, so inside a function you cannot access variables in the global scope.

Variable Scope

within user-defined functions a local function scope is introduced. Any variable used inside a function is by default limited to the local function scope

About included files, the manual states:

When a file is included, the code it contains inherits the variable scope of the line on which the include occurs.

So if you include something in a function, the included file's scope will be that of the function's.

UPDATE: Looking at your code example edited into the question, global $newClass; as the first line of the function should make it working.

$newClass = new myClass();
require_once("path to my file");

----- inside required file -----
function someFunction() {
     global $newClass;
     $newClass->someMethod(); 
}

Be aware though that using global can quickly make your code more difficult to maintain. Don't rely on the global scope, you can pass the object to the function as a parameter, or use a Singleton/Registry class (some tend to argue against the latter, but depending on the case it can be a cleaner solution).