7 calls to drush_module_exists()

DrupalBoot::drush_enforce_requirement_drupal_dependencies in lib/Drush/Boot/DrupalBoot.php
Check that a command has its declared dependencies available or have no dependencies.
drush_config_import_validate in commands/core/config.drush.inc
drush_get_projects in commands/pm/pm.drush.inc
Obtain an array of installed projects off the extensions available.
drush_hook_pre_pm_enable in ./drush.api.php
Automatically download project dependencies at pm-enable time.
drush_load_engine in includes/engines.inc
Loads and validate an engine of the given type.
drush_role_perm in commands/core/role.drush.inc
Implement permission add / remove operations.
package_handler_validate in commands/pm/package_handler/git_drupalorg.inc
Validate this package handler can run.