provide a harmonized entity_form() function

Very interesting, subscribing.

+++ contrib/profile2_page.moduleundefined
@@ -163,6 +164,15 @@ function profile2_page_uri_callback($profile) {
+  form_load_include($form_state, 'inc', 'profile2_page');

$form_state is undefined. Should it be an empty array?

I'm looking at it for Message - I'd like to provide a UI for users to CRUD message (i.e. message instance not message type).

Oink.

+++ entity.module
@@ -411,6 +418,38 @@ function entity_access($op, $entity_type, $entity = NULL, $account = NULL) {
+    return $info['form callback']($entity, $entity_type);

First arguments should obviously be $form, $form_state...

:(

+++ entity.module
@@ -953,7 +995,7 @@ function entity_forms($form_id, $args) {
+function entity_ui_get_form($entity_type, $entity, $op = 'edit', $form_state = array()) {

$form_state is never empty in D7. Should at least be form_state_defaults(), prepared and provided by the function invoking the hook.

sub

entity_form() is supposed to build and process the form for you - there is no possibility to embed forms in others or similar. That way there is no point or possibility to customize $form and $form_state.

This prevents entity_form from being used in ctools modals. That needs a custom form_state.
A possible workaround for that is entity_metadata_form_id_* to complement entity_metadata_form_*.

function entity_metadata_form_id_node(&$form, &$form_state, $node) {
  // Pre-populate the form-state with the right form include.
  $form_state['build_info']['args'] = array($node);
  form_load_include($form_state, 'inc', 'node', 'node.pages');
  return $node->type . '_node_form';
}
function entity_metadata_form_node(&$form, &$form_state, $node) {
  $form_id = entity_metadata_form_id_node($form, $form_state, $node);
  return drupal_build_form($form_id, $form_state);
}

Unsure about the &$form part, but this would really help with the ctools modal stuff.

Opened #1437902: Allow custom $form_state to be used with entity_form()