switch_to_post() stack implementation (similar to switch_to_blog()) for WordPress

README.txt

# Switch to Post README

## Overview
switch_to_post() stack implementation (similar to switch_to_blog()) for WordPress

## Questions
1. Do we want to still switch to post if the get_post fails?
2. Have a (bool) return value based on get_post?

## Test Steps
1. Include the `debug.php` and `test-actions.php` file
2. Alter Post IDs in test-actions.php to valid post IDs for your WP install

debug.php

<?php
function debug_post_stack() {
	global $WP_POST_STACK;
	echo '<pre>';
	print_r($WP_POST_STACK);
	echo '</pre>';
}

function debug_post($msg = '') {
	global $post;
	echo '<h2>'.$msg.'</h2>';
	echo '<pre>';
	print_r($post->ID.' :: '.$post->post_title);
	echo '</pre>';
	echo '<hr />';
}
add_action('switch_to_post', 'debug_post');
add_action('restore_post', 'debug_post');

test-actions.php

<?php
require_once 'debug.php';

function test_init() {
	// First post
	debug_post('Original'); //440

	// Switch to a post
	switch_to_post(2); // 2
	restore_post();

	switch_to_post(20);

		switch_to_post(400);
			switch_to_post(461);
			restore_post();
		restore_post();

		switch_to_post(5);
		restore_post();

	restore_post();
	
	debug_post('Finally, should be back');
}
add_action('wp', 'test_init');

wp-switch-to-post.php

<?php

$WP_POST_STACK = array();

function switch_to_post($post_id) {
	global $WP_POST_STACK, $post;
	
	// Initialize the stack with very first $post->ID
	if (!count($WP_POST_STACK)) {
		$WP_POST_STACK[] = $post->ID;
	}
	
	// Stick our new post_id onto the end
	$WP_POST_STACK[] = $post_id;
	$post = get_post($post_id);
	setup_postdata($post);
	
	do_action('switch_to_post', $post_id);
}

function restore_post() {
	global $WP_POST_STACK, $post;

	// If we don't have anything to knock off, just return
	if (!is_array($WP_POST_STACK) || !count($WP_POST_STACK)) {
		return;
	}
	
	// Remove the current post_id off the stack
	$removed_post_id = array_pop($WP_POST_STACK);
	
	// Get last value of the array but leave it on the array
	$post_id = end($WP_POST_STACK);
	if ($post_id !== false) {
		$post = get_post($post_id);
		setup_postdata($post);
	}
	
	do_action('restore_post', $post_id, $removed_post_id);
}

Will do