[D7] Allow the use of callbacks instead of global functions in theme processor functions

A step further into OOP, Thanks. :D! Fix worked perfectly.

Nice work, pending commit!

See comment at #2652814-8: Allow the use of callbacks for element value callbacks and batch API redirect callbacks which applies here too.

The is_callable() part we definitely can do, the $function => call_user_func_array() we should remove for now.

Adding Novice tag as it should be simple to just leave is_callable().

Committed and pushed to 7.x! Thanks!

I fixed the removal of the call_user_func_array() on commit and also made it possible to use any callable for theme functions.

diff --git a/includes/theme.inc b/includes/theme.inc
index ff54d6e..991beea 100644
--- a/includes/theme.inc
+++ b/includes/theme.inc
@@ -1119,7 +1119,7 @@ function theme($hook, $variables = array()) {
     foreach (array('preprocess functions', 'process functions') as $phase) {
       if (!empty($info[$phase])) {
         foreach ($info[$phase] as $processor_function) {
-          if (function_exists($processor_function)) {
+          if (is_callable($processor_function)) {
             // We don't want a poorly behaved process function changing $hook.
             $hook_clone = $hook;
             $processor_function($variables, $hook_clone);
@@ -1157,7 +1157,7 @@ function theme($hook, $variables = array()) {
   // Generate the output using either a function or a template.
   $output = '';
   if (isset($info['function'])) {
-    if (function_exists($info['function'])) {
+    if (is_callable($info['function'])) {
       $output = $info['function']($variables);
     }
   }

This is still present in D8 and needs to be fixed there first.

D8 issue: #2760659: Allow the use of callbacks instead of global functions in preprocess function callbacks

I think this is small enough to be a task.

Adding the issue that we collectively add tests for these changes (correct me if I'm wrong please).

Moving to 7.70 for now as waiting for D8 commit.