[wp-trac] [WordPress Trac] #8833: extract pluggable.php function logic into separate functions

[WordPress Trac]

#8833: extract pluggable.php function logic into separate functions
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 Reporter:  wnorris                   |       Owner:  Viper007Bond
     Type:  enhancement               |      Status:  new
 Priority:  normal                    |   Milestone:  Future Release
Component:  Plugins                   |     Version:  2.8
 Severity:  normal                    |  Resolution:
 Keywords:  needs-patch dev-feedback  |
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Changes (by johnbillion):

 * keywords:  needs-patch dev-feedback close => needs-patch dev-feedback


Comment:

 I know there's not a lot of traction on this ticket, but I'd like to add a
 bit of feedback (partly because it was recently mentioned again on
 hackers).

 With more than one plugin trying to override a given pluggable function,
 there will only be one winner. The problem is that some of the pluggable
 functions are too wide in scope, and two different plugins may be trying
 to override the same pluggable function in its entirety just to change on
 bit of its functionality.

 I think many of the pluggable functions should be split into multiple
 functions, with their individual bits of functionality being filterable.
 This way, plugins can override (and "win") more tightly focused functions.

 One example is `wp_mail()`, which does far more than just send an email.
 It parses headers (including the 'from', 'cc' and 'bcc' fields), sets the
 'from' name and address, sets content types, deals with charsets, adds
 custom headers, adds attachments, and finally sends an email.

 Changing this from from being pluggable to being filterable doesn't
 overcome the issue where you may want to run multiple email-related
 plugins at the same time, such as one which gives you HTML emails and one
 which sends your emails through an email delivery service.

 Another example is the various notification functions such as
 `wp_notify_moderator()`, `wp_notify_postauthor()` and
 `wp_new_user_notification()`. These functions have a mixture of logic in
 them determining whether or not to send a notification, the notification
 message itself, and additional stuff such as the 'from' headers in the
 email. What a user cannot do, for example, is install one plugin to change
 the text in these emails and another plugin which allows you to control
 when and whether these notifications are sent.

 A good first step would be to look at splitting some of these functions
 up, and deciding which of the subsequent functions should have their
 output filterable (eg. the text sent in notification emails) and which
 should have their callback function filterable (eg. the function which
 actually sends email).

 I'd be willing to start looking at this over the next few weeks if it'll
 get some traction.

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Ticket URL: <http://core.trac.wordpress.org/ticket/8833#comment:24>
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