get_defined_functions - PHP code example

Using the PHP Function Get_Defined_Functions()

Get_defined_functions() is an inbuilt function in PHP which returns the list of functions that are defined in the script. The list contains the built-in functions and the user-defined ones too. The returned value has a multidimensional array format with the index internal for the built-in functions and the index user for the user defined functions.

A function in PHP is a block of code that can be called and executed at run time. It is a way to break your program into smaller pieces that can be independently executed, making your program more efficient and modular. Functions allow you to write complex and reusable code that can be used in other parts of the program.

When you call a function, it takes some input data and processes it. It will then return a result that can be used by the rest of your code. This allows your code to be more modular and readable. It also makes it easier to debug your program because you can see exactly what function is causing the problem.

Functions can be used to perform any task in PHP including logging, error reporting, database access and even creating web forms. It is important to understand how they work so that you can use them properly in your code. In this article, we will take a look at the basic principles of how a function works and then we’ll explore some real-world examples of defining and using a php function.

get_defined_functions example

$fullyQualifiedFunctionName = substr($message, $prefixLen, -$notFoundSuffixLen);
        if (false !== $namespaceSeparatorIndex = strrpos($fullyQualifiedFunctionName, '\\')) {
            $functionName = substr($fullyQualifiedFunctionName, $namespaceSeparatorIndex + 1);
            $namespacePrefix = substr($fullyQualifiedFunctionName, 0, $namespaceSeparatorIndex);
            $message = sprintf('Attempted to call function "%s" from namespace "%s".', $functionName, $namespacePrefix);
        } else {
            $functionName = $fullyQualifiedFunctionName;
            $message = sprintf('Attempted to call function "%s" from the global namespace.', $functionName);
        }

        $candidates = [];
        foreach (get_defined_functions() as $type => $definedFunctionNames) {
            foreach ($definedFunctionNames as $definedFunctionName) {
                if (false !== $namespaceSeparatorIndex = strrpos($definedFunctionName, '\\')) {
                    $definedFunctionNameBasename = substr($definedFunctionName, $namespaceSeparatorIndex + 1);
                } else {
                    $definedFunctionNameBasename = $definedFunctionName;
                }

                if ($definedFunctionNameBasename === $functionName) {
                    $candidates[] = '\\'.$definedFunctionName;
                }
            }
        }

namespace Drupal\Core\Theme;

use Drupal\Tests\Core\Theme\RegistryTest;

/** * Overrides get_defined_functions() with a configurable mock. */
function get_defined_functions() {
return RegistryTest::$functions ?: \get_defined_functions();
}

return [];
  }

  /** * Gets all available update functions. * * @return callable[] * A list of update functions. */
  protected function getAvailableUpdateFunctions() {
    $regexp = '/^(?<extension>.+)_' . $this->updateType . '_(?<name>.+)$/';
    $functions = get_defined_functions();

    $updates = [];
    foreach (preg_grep('/_' . $this->updateType . '_/', $functions['user']) as $function) {
      // If this function is an extension update function, add it to the list of       // extension updates.       if (preg_match($regexp, $function, $matches)) {
        if (in_array($matches['extension'], $this->enabledExtensions)) {
          $function_name = $matches['extension'] . '_' . $this->updateType . '_' . $matches['name'];
          if ($this->updateType === 'post_update') {
            $removed = array_keys($this->getRemovedPostUpdates($matches['extension']));
            if (array_search($function_name, $removed) !== FALSE) {

public function getAvailableUpdates(string $module): array {
    if (!isset($this->allAvailableSchemaVersions[$module])) {
      $this->allAvailableSchemaVersions[$module] = [];

      foreach ($this->enabledModules as $enabled_module) {
        $this->allAvailableSchemaVersions[$enabled_module] = [];
      }

      // Prepare regular expression to match all possible defined       // hook_update_N().       $regexp = '/^(?<module>.+)_update_(?<version>\d+)$/';
      $functions = get_defined_functions();
      // Narrow this down to functions ending with an integer, since all       // hook_update_N() functions end this way, and there are other       // possible functions which match '_update_'. We use preg_grep() here       // since looping through all PHP functions can take significant page       // execution time and this function is called on every administrative page       // via system_requirements().       foreach (preg_grep('/_\d+$/', $functions['user']) as $function) {
        // If this function is a module update function, add it to the list of         // module updates.         if (preg_match($regexp, $function, $matches)) {
          $this->allAvailableSchemaVersions[$matches['module']][] = (int) $matches['version'];
        }

/** * Gets all user functions grouped by the word before the first underscore. * * @param $prefixes * An array of function prefixes by which the list can be limited. * * @return array * Functions grouped by the first prefix. */
  public function getPrefixGroupedUserFunctions($prefixes = []) {
    $functions = get_defined_functions();

    // If a list of prefixes is supplied, trim down the list to those items     // only as efficiently as possible.     if ($prefixes) {
      $theme_functions = preg_grep('/^(' . implode(')|(', $prefixes) . ')_/', $functions['user']);
    }
    else {
      $theme_functions = $functions['user'];
    }

    $grouped_functions = [];