[development] Overriding function declared in another module

[Randy Fay]

The problem here is really important, regardless of the documentation.

In Drupal 7, the problem has been resolved (and the doc may well be wrong).
In D7, hook_form_alter() and hook_form_FORMID_alter() no longer compete in
the inappropriate way they did in D6 - they fire in order by weight. So a
given module weight will execute the form_alter and the formid_alter at
about the same time.

In Drupal 6, you *very* often can't achieve what you want to with
hook_form_FORMID_alter() because *all* of the hook_form_alters run after all
of the hook_form_FORMID_alters. That means that you *can't* alter a prepared
node form successfully with hook_form_FORMID_alter() because all of the
things that have built up the form (using hook_form_alter()) haven't run
yet. So the form doesn't even look right yet. hook_form_alter() is often the
only way around this.

As a general statement, hook_form_FORM_ID_alter() in Drupal 6 is often not
useful because of this and you *always* have to be aware of this problem.
And in general, this problem is fixed very nicely in Drupal 7. Thanks
effulgentsia and sun!

-Randy

On Tue, Jan 18, 2011 at 5:37 PM, Jennifer Hodgdon <yahgrp at poplarware.com>wrote:

> I just filed an issue:
> http://drupal.org/node/1031458
>
> The doc is only incorrect in D6. In D7 the order has changed.
>
>   --Jennifer
>
>
>
> On 1/18/2011 7:37 AM, Justin Ellison wrote:
>
>> Code speaks truth, you're correct.  However, there's some
>> contradicting documentation.
>>
>>  From
>>> http://api.drupal.org/api/drupal/modules--system--system.api.php/function/hook_form_alter/7
>>> :
>>>
>> "For each module (in system weight order) the general form alter hook
>> implementation is invoked first, then the form ID specific alter
>> implementation is called."
>>
>>  From
>>> http://api.drupal.org/api/drupal/developer--hooks--core.php/function/hook_form_FORM_ID_alter/6
>>> :
>>>
>> "Note that this hook fires before hook_form_alter(). Therefore all
>> implementations of hook_form_FORM_ID_alter() will run before all
>> implementations of hook_form_alter(), regardless of the module order."
>>
>> Unfortunately, Google returns the former link first, which must've
>> been what I learned from.
>>
>> Sorry for any confusion,
>>
>> Justin
>>
>> On Tue, Jan 18, 2011 at 9:26 AM, Steve Ringwood<nevets at tds.net>  wrote:
>>
>>> Justin
>>>
>>>    Not sure what you are referring to in the docs for hook_form_alter but
>>> here is the relavent code
>>>    from form.inc, function drupal_prepare_form().
>>>
>>>  $data =&$form;
>>>  $data['__drupal_alter_by_ref'] = array(&$form_state);
>>>  drupal_alter('form_'. $form_id, $data);<<  Form ID specific call
>>>
>>>  // __drupal_alter_by_ref is unset in the drupal_alter() function, we
>>> need
>>>  // to repopulate it to ensure both calls get the data.
>>>  $data['__drupal_alter_by_ref'] = array(&$form_state);
>>>  drupal_alter('form', $data, $form_id);<<  General call (hook_form_alter)
>>>
>>> Nevets
>>>
>>>
>>>
>>
>
> --
> Jennifer Hodgdon * Poplar ProductivityWare
> www.poplarware.com
> Drupal web sites and custom Drupal modules
>
>


-- 
Randy Fay
Drupal Module and Site Development
randy at randyfay.com
+1  970.462.7450
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