Returning Variables back into a template

Question

If I put a function that I want to use in a template I can put it into functions.php

function myfunction(){
echo 'My String';
}

add_action('myfunction','myfunction');

and in a template file put:

do_action('myfunction');

This appears to only work if writing something out to the screen. If I wanted to return a variable instead to the page. E.g.

function myfunction(){
return 'My String';
}

$string = do_action('myfunction');

and capture it instead of print it. How would I do it?

Answer 1

There's filters for that.

Example:

add_filter( 'template_filter', 'wpse_102706_filter_callback', 10, 2 );
function wpse_102706_filter_callback( $defaults, $case )
{
    $args = wp_parse_args( array(
        'some_key' => 'some_modified_value'
    ), $defaults );

    return $args
}

Then in your template just add in the defaults:

apply_filters( 'template_filter', array( 'some_key' => 'default_val' ), 'single' );

More info in Codex about the Plugins API.