[drupal-devel] [feature] Dependency system to solve forum without comment problem

chx drupal-devel at drupal.org
Sun Mar 6 11:08:39 UTC 2005

Issue status update for http://drupal.org/node/18447

 Project:      Drupal
 Version:      cvs
 Component:    system.module
 Category:     feature requests
 Priority:     normal
 Assigned to:  chx
 Reported by:  chx
 Updated by:   chx
 Status:       patch
 Attachment:   http://drupal.org/files/issues/depend_4.patch (3.27 KB)

Minor things: default hook_info key shall be called 'depends' not
'required' (Adrian). Message should be 'enabled' for consistency


Previous comments:

March 6, 2005 - 01:55 : chx

Attachment: http://drupal.org/files/issues/depend.patch (3.22 KB)

As discussed on the developer list. This was surprisingly easy. There is
still an issue: t('The configuration options have been saved.') is
displayed more than once if there is a dependency forced module switch
on. I have tried something (you'll see) for some reason it does not
Number of page reloads can be decreased if Drupal could be
reinitialized after system_listing_save instead of redirecting but I
doubt this would be feasible.
Although I marked this is feature request, this is more a usability
issue (for the forum-comment dependency) and as a side effect it is a
useful feature, too (for any other module "bundles").
I want criticism! I'd like to get torn apart by wild animals. Heavy! 
Eaten by some squirrels.


March 6, 2005 - 02:22 : clydefrog

Forgive me if I'm mistaken, but shouldn't forum_depends return an array?


March 6, 2005 - 02:26 : javanaut

I think allowing for both required dependencies as well as optional ones
would make it practical for a package management tool to be created.  I
like it, though, and I think being able to programatically enforce (or
at least notify users about) dependencies would assist users who refuse
to RTFM.
>From my drupal-devel comment, here's how I would suggest formatting the

function filestore2_depends() {
 return array('required'=>array('fscache'),


March 6, 2005 - 02:29 : chx

If you take a look at module_invoke_all, you will see that a string is
fine, 'cos if you return a string it does $result[]
However, an associative array is not good with module_invoke_all 'cos
for returned arrays there is an array_merge where "If the input arrays
have the same string keys, then the later value for that key will
overwrite the previous one."


March 6, 2005 - 02:33 : javanaut

Ok, how about it taking a parameter?

function filestore2_depends($dep_type='required') {
$deps = array('required'=>array('fscache'),
return $deps[$dep_type];

Then, for required dependencies, pass a 'required' argument, and
optional ones could take an 'optional' argument.


March 6, 2005 - 03:00 : chx

Attachment: http://drupal.org/files/issues/depend_0.patch (3.6 KB)

I would leave associative arrays for the future. As we do not have a
package tool, there is little use of 'optional' -- I'd like to get this
into 4.6
After testing the patch, I have changed something, which I should not
have done, so another version is attached.


March 6, 2005 - 03:11 : chx

Attachment: http://drupal.org/files/issues/depend_1.patch (4.37 KB)

This one should really work...


March 6, 2005 - 03:12 : chx

Attachment: http://drupal.org/files/issues/depend_2.patch (3.15 KB)


March 6, 2005 - 05:13 : gordon

Not only is this something that I have wanted for filestore2 for quite
a while, but has not been on my priority list. But this would be
extremely useful for the ecommerce modules, as there seems to be alot
of interdependancy.
Also on a side note, it would also be good for a module to be able to
reject an enabling. So if the module is going to stop drupal from
running if it does have its tables created, it will inform the user and
not be turned on. This could actually be done allowing the dependancy
hook to do some checking and so stop the module from being able to be


March 6, 2005 - 09:19 : mathias

This would make installing the ecommerce package easier given that
modules are no longer listed alphabetically from within their
subdirectories.  The modules are scattered all over the page unless I
adopt some sort of ec_ prefix to module naming.
I wonder how Adrian's installer handles dependencies?


March 6, 2005 - 11:42 : adrian

My installer doesn't currently handle dependencies, and I am not
convinced this should go into 4.6.
There's more to dependency checking than just 'depends' including fun
things like circular dependencies and version checking.
Once we have versioning for drupal modules / schemas .. we can look at
this again. 
Vlado apparently has dependency checking code already built, that he is
going to donate to the installer effort.


March 6, 2005 - 11:57 : chx

Attachment: http://drupal.org/files/issues/depend_3.patch (3.26 KB)

Well, I know there could be problems. However, circular dependecy is
handled with my code. You have module A, this depends on B, this
depends on C which depends on A. You tick A, press Save. Next listing
will tick B instead of you, press Save. Next listing will tick C
instead of you, press Save. Next listing will be happy, 'cos A is on.
Adrian convinced me that taking a parameter is a good thing, so it's
in. And he asked for calling the hook _info. So be it. And he pointed
out that I do not understand drupal_set_message which was true. So now
the status message is now displayed only once. Shall I protect the new
error message from such a duplication?
And please, get this simple system into 4.6 'cos (as already stated)
the forum-comment dependency has threads on drupal.org already so it
could be called a bug.

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