[wp-trac] [WordPress Trac] #14671: Deprecate the "accepted args" argument in add_filter() and add_action()

[WordPress Trac]

#14671: Deprecate the "accepted args" argument in add_filter() and add_action()
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 Reporter:  markjaquith  |       Owner:
     Type:  enhancement  |      Status:  new
 Priority:  normal       |   Milestone:  Future Release
Component:  Plugins      |     Version:
 Severity:  normal       |  Resolution:
 Keywords:  has-patch    |
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Comment (by westonruter):

 I had the idea a couple years ago to use PHP's Reflection capabilities to
 introspect the number of arguments defined on the function so that the use
 of the `$accepted_args` 4th argument could be largely eliminated (as
 5ubliminal also suggested above). At that time, WordPress still was
 required to support PHP4, and so this was a dead end since Reflection was
 introduced in PHP5. Now, however, since WordPress requires PHP≥5.2, it is
 now safe to use Reflection and we can use it make our plugin code more
 DRY. In my supplied patch, note that you can still supply the 4th
 `$accepted_args` parameter, and this will override any attempt to get the
 argument count via Reflection; this is useful if you are using a function
 as a hook handler which has optional arguments which may get inadvertently
 set when the hook is executed with extra arguments.

 Regarding performance, I did a comparison of the execution time when using
 Reflection vs. the baseline code that is in trunk. The test script can be
 found at https://gist.github.com/4581512#file-test-php

 Here is the results of the reference baseline trunk plugins.php:

 {{{
 $ wp eval-file test.php
 Running original plugin.php
 Iteration count 100000
 Testing function...
  2.842000 seconds
 Testing method...
  2.881264 seconds
 Testing closure...
  2.831295 seconds
 }}}

 And then here is the results with my patch:

 {{{
 $ wp eval-file test.php
 Running patched plugin.php
 Iteration count 100000
 Testing function...
  3.783207 seconds
 Testing method...
  3.864082 seconds
 Testing closure...
  3.748331 seconds
 }}}

 As you can see at over 100,000 iterations, the version with Reflection
 runs about a third slower. I did try a version of my patch that included
 static caching the Reflection calls, but it seems the logic to generate
 the cache key (utilizing `spl_object_hash()`) actually is about the same
 as invoking Reflection's `getNumberOfParameters` method; after repeated
 tests, the version of the patch with and the version without would
 consistently alternate in being faster. Nevertheless, the patch with the
 cache is also available: https://gist.github.com/4581512#file-plugin-php-
 alternate-patch

 Personally, I think the usability benefits we gain by not having to supply
 the 4th argument outweighs the overall performance hit to use Reflection
 to introspect the number of arguments.

 I have not yet run the patch through the unit tests.

-- 
Ticket URL: <http://core.trac.wordpress.org/ticket/14671#comment:25>
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