Can I make a PHP function "private" in a script? - php

Question

I want some functions to be not visible when required, but visible in the script they belong to.
For example:
required.php:
<?php
function privateFunction() {
echo 'from private function\n';
}
echo 'from required.php: ';
privateFunction();
index.php:
<?php
require './required.php';
echo 'from index.php: ';
privateFunction(); // I want this to give an error like "private function called outside the script it has been declared".
I have already tried making the function private, but it only gives a parse error.

Answer 1

required.php:
<?php
class A {
private function privateFunction() {
echo 'from private function\n';
}
}

Answer 2

This is a probably a bad idea in general (see comments above), but the following should do what you're asking.
It makes use of debug_backtrace() to grab the file name of the function then the file name of the function's caller, and compares them. If they don't match, it throws an exception:
function assertCalledByCurrentScript(): void
{
$backtrace = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS);
if (isset($backtrace[1]) && $backtrace[0]['file'] !== $backtrace[1]['file']) {
throw new \BadFunctionCallException("Cannot call {$backtrace[1]['function']} from outside of its defining script.");
}
}
Then use it like this:
function privateFunction()
{
assertCalledByCurrentScript();
// rest of your "private" function here
}

Answer 3

Basically only option you have is to hide private stuff inside class:
//Your file
class MyClass
{
public static function myAction()
{
$internalStuff = self::internalStuff();
return 'Using this function you can get what is inside internalStuff: ' . $internalStuff;
}
private static function internalStuff()
{
return 'Some internal stuff not accessible from outside';
}
}
function myAction()
{
return MyClass::myAction();
}
//Otherfile
//require yourfile.php
//You can only use `myAction` as function
echo myAction();
//Or call
echo MyClass::myAction();
//But you cannot use `internalStuff
echo MyClass::internalStuff();