How to pass variables to custom filter from multiple functions

Question

I am trying to pass a variable from a function (that renders a shortcode) to another which enqueues google fonts. I am using filters for that. Since the functions are hooked to add_shortcode, I guess I can't add the filter directly.

I am using the mediator function for that. When I do a print_r for the mediator function in wp_footer, its showing the variable, but not (showing empty array) when I hook it to add_filter to the enqueue function and print it to wp_footer.

function first_shortcode( $atts , $content = null ) {

    $atts = shortcode_atts(
        array(
            'typography' => '',
        ),
        $atts
    );

    //Other shortcode stuffs

    if ( $atts['typography'] ) {
        $typo = $atts['typography'];

        $font = array();
        $font['family'] = $typo['font'];
        $font['weight'] = $typo['weight'];

        googlefont_filter_callback( $font );
    }

}
add_shortcode( 'first', 'first_shortcode' );

function second_shortcode( $atts , $content = null ) {

    $atts = shortcode_atts(
        array(
            'typography' => '',
        ),
        $atts
    );

    //Other shortcode stuffs

    if ( $atts['typography'] ) {
        $typo = $atts['typography'];

        $font = array();
        $font['family'] = $typo['font'];
        $font['weight'] = $typo['weight'];

        googlefont_filter_callback( $font );
    }

}
add_shortcode( 'first', 'second_shortcode' );  

The mediator function:

function googlefont_filter_callback( $fonts=array() ) {

    return $fonts;

}
add_filter( 'googlefont_loader', 'googlefont_filter_callback' );  

And the function that enqueues the fonts:

function googlefont_loader( $fonts=array() ) {

    $fonts = array();
    $fonts = apply_filters( 'googlefont_loader', $fonts );

    $new_array = array();

    foreach ($fonts as $font){
        $new_value = !empty($new_array[$font['family']]) ? $new_array[$font['family']].','.$font['weight'] : $font['weight'];
        $new_array[$font['family']] =  $new_value;
    }

    /*
    $out = '';
    foreach( $new_array as $family => $weight ) {

        $out .= $family . ':' . $weight . '|';  
    }
    if ( !empty($fonts) ) {
        wp_register_style( 'purewpns-googlefonts', '//fonts.googleapis.com/css?family=' . rtrim($out, '|') );
        wp_enqueue_style( 'purewpns-googlefonts' );
    }
    */

    echo '<pre>' . print_r( $fonts, true ). '</pre>';

}
add_action( 'wp_footer', 'purewpns_googlefont_loader' );
//add_action( 'wp_enqueue_scripts', 'purewpns_googlefont_loader' );

Now, the echo in googlefont_loader returns an empty array

Array
(
)  

What I am doing wrong? Or, is it due to the firing timings of hooks?

Answer 1

I think from your code

add_action( 'wp_footer', 'purewpns_googlefont_loader' );

Function purewpns_googlefont_loader maybe typo mistake.

---

You use the action wp_footer and added empty array which obviously print empty array.

---

Okay. You can use:

googlefont_filter_callback( $font );

Except

$fonts = apply_filters( 'googlefont_loader', $fonts );

In function googlefont_loader()

And add filter in function googlefont_filter_callback like:

function googlefont_filter_callback( $fonts=array() ) {
return apply_filters( 'googlefont_loader', $fonts );
}

---

Now you'll be able to access fonts from both short code.

E.g.

add_filter( 'googlefont_loader' function( $fonts ) {
 var_dump( $fonts);
return $fonts;
});

But it affect on both short code. You can introduce another individual filters for each shortcode.