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Is it possible to hook 3 different functions to the same filter conditionally, like:

    add_filter('the_content', 'fnc_1');
else if(b){
    add_filter('the_content', 'fnc_2');
    add_filter('the_content', 'fnc_3');

Or if this isn't possible, then can I pass an additional argument to the same function to flag my 3 different conditions? Something like:

    add_filter('the_content', 'fnc_1', 'condition_a');
else if(b){
    add_filter('the_content', 'fnc_1', 'condition_b');
    add_filter('the_content', 'fnc_1', 'condition_c');

All I could find from my reading is that it has to do something with apply_filters, but couldn't get around it.

Please can anyone tell me how to achieve this? Thanks!

share|improve this question
Method 1 is completely valid. Have you tried it yourself? Method 2 will not work, since add_filter does not allow you to pass additional arguments. – soulseekah Oct 19 '11 at 5:57
Yes... I tried the first one, it works! Thanks! – Rutwick Gangurde Oct 19 '11 at 5:58
For method 2, you can wrap a custom filter over a defined filter and conditionally have it pass a second argument, I think. But I don't see any reason to other than for education. – soulseekah Oct 19 '11 at 6:01
Know a place where I can see an example? Like a blog or a tut? – Rutwick Gangurde Oct 19 '11 at 6:03
Education it is then... check my answer :) – soulseekah Oct 19 '11 at 6:17
up vote 4 down vote accepted

Since it does appear to be an interesting question, I'll go ahead an compile an answer.

Method 1

Totally fine, will work. Here's the compact piece of code I used to test it:

function fnc_1( $content ) { return 'func1 :: '.$content;   }
function fnc_2( $content ) { return 'func2 :: '.$content;   }
function fnc_3( $content ) { return 'func3 :: '.$content;   }

$a = false;
$b = false;

if ( $a ) add_filter( 'the_content', 'fnc_1' );
elseif ( $b ) add_filter( 'the_content', 'fnc_2' );
else add_filter( 'the_content', 'fnc_3' );

Method 2

add_filter does not allow you to pass additional arguments to the filter function, but if you really need to share one function you can wrap a custom filter around the filter like so:

add_filter( 'wpse31470_filter_wrapper', 'wpse31470_filter_wrapper_func', null, 2 );

function wpse31470_filter_wrapper_func( $content, $condition ) {
    if ( $condition ) return 'TRUE :: '.$content;
    else return 'FALSE ::'.$content;

add_filter( 'the_content', 'wpse31470_the_content_filter' );
function wpse31470_the_content_filter( $content ) {
    $condition = true;
    return apply_filters( 'wpse31470_filter_wrapper', $content, $condition );

The purpose of the wpse31470_the_content_filter is to wrap the argument supplied by the_content filter and pass it on to your own wpse31470_filter_wrapper along with any additional arguments.

share|improve this answer
Awesome! Thanks a lot... I'm trying the 2nd apply_filters method right away, cause if it works, many of my workarounds will go away! +1! – Rutwick Gangurde Oct 19 '11 at 6:35
Glad to have been of help. Let me know if you stumble upon any questions or suggestions. And don't forget to improve your accept rate (67% is low) in order to get more quality answers in our community wink – soulseekah Oct 19 '11 at 6:46
Yes indeed! If I stumble, I won't hesitate to ask you! And there goes the 'accept' ;) – Rutwick Gangurde Oct 19 '11 at 6:49

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