[development] module_exists vs. functions_exists?

[Earnie Boyd]

Quoting Greg Knaddison - GVS <Greg at GrowingVentureSolutions.com>:

> Hi,
>
> In building some contrib modules that interact with other modules I
> often find myself writing something like:
>
> if (module_exists('module_name')) {
>  $foo = module_name_api_function($bar);
> }
>
> This seems to be pretty common across core and contrib.  I'd even call
> it standard.
>
> Another option would be:
>
> if (function_exists('module_name_api_function')) {
>  $foo = module_name_api_function($bar);
> }
>
> The benefit of the second format is that if/when module_name's
> maintainer decides to rewrite module_name and change all their
> functions then my module may simply stop interacting with it rather
> than failing on a function not found error.
>
> The benefit of the first format is that it fails quickly and is likely
> to generate a bug report with a very clear solution.
>
> Thoughts?
>

I would rather ask the interacting modules to insert a 
MODULE_FOO_VERSION and check for the constant being defined and defined 
to the version you expect.  The module_exists function used with 
function_exists as you suggest is a good fall back for not having 
MODULE_FOO_VERSION.

Earnie -- http://for-my-kids.com/
-- http://give-me-an-offer.com/