Scott Reilly

<p>A widget that can act as a duplicate of another widget (for synchronized use in another sidebar)</p>
<p>Define a widget once, use it in multiple sidebars.  This saves you from having to manually configure each copy of the widget and later having to worry about keeping them in sync should you ever need to make any changes.  Particularly useful for those who define logic in their themes to conditionally include different versions of a sidebar depending on what template is being shown. Depending on use, it is an alternative to plugins that introduce in-widget logic to determine when widgets should be visible (Widget Logic, Section Widget, Conditional Widgets, etc).</p>
<p>Quick overview of what this plugin does:</p>
<ul>
<li>Adds a widget called “Duplicate”. The widget’s only setting is a dropdown listing all active widgets.  The selected widget will be the widget duplicated by the duplicate widget.</li>
<li>A duplicate widget shows the same title and content as its source widget, even if those values later get changed in the source widget.</li>
<li>A widget can be duplicated any number of times and can appear multiple times within the same page. (Yes, even within the same sidebar, though why would you do that?)</li>
<li>A duplicate widget will abide by the configuration of the sidebar it is placed in, not the configuration of the sidebar containing the source widget.  So it uses ‘before_widget’, ‘after_widget’, ‘before_title’, ‘after_title’ values of its own sidebar.</li>
<li>Widgets that are duplicated will have “[D]” prepended to their name in the widget titlebar in the admin to denote they have duplicates.  Also, at the bottom of the widget’s configuration form (when the widget is expanded), a short blurb also explains that the widget has duplicate(s) and a count of how many duplicates it has.</li>
<li>If a widget is deactivated or deleted, if it has any duplicates, they get deleted as well.</li>
<li>The widget id and widget type of the source widget are included as HTML classes in the duplicate widget’s markup.</li>
</ul>
<p>Links: <a href="http://coffee2code.com/wp-plugins/duplicate-widget/" rel="nofollow ugc">Plugin Homepage</a> | <a href="https://wordpress.org/extend/plugins/duplicate-widget/" rel="ugc">Plugin Directory Page</a> | <a href="http://coffee2code.com" rel="nofollow ugc">Author Homepage</a></p>
<h3>Filters</h3>
<p>The plugin exposes four actions for hooking.  Typically, customizations utilizing these hooks would be put into your active theme’s functions.php file, or used by another plugin.</p>
<h4>c2c_before_duplicate_widget (action)</h4>
<p>The ‘c2c_before_duplicate_widget’ hook allows you to output text, or perform some sort of action, just before the output of the duplicate widget.</p>
<p>Arguments:</p>
<ul>
<li>$instance (array) : The settings for the widget instance (namely: title and widget_to_duplicate)</li>
<li>$args (array) : The configuration for the widget and sidebar</li>
</ul>
<p>Example:</p>
<pre><code>// Output an opening <div> before duplicate widget content
add_action( 'c2c_before_duplicate_widget', 'my_c2c_before_duplicate_widget', 10, 2 );
function my_c2c_before_duplicate_widget( $instance, $args ) {
    echo '<div class="a_duplicate_widget">;
}
</code></pre>
<h4>c2c_after_duplicate_widget (action)</h4>
<p>The ‘c2c_after_duplicate_widget’ hook allows you to output text, or perform some sort of action, just after the output of the duplicate widget.</p>
<p>Arguments:</p>
<ul>
<li>$instance (array) : The settings for the widget instance (namely: title and widget_to_duplicate)</li>
<li>$args (array) : The configuration for the widget and sidebar</li>
</ul>
<p>Example:</p>
<pre><code>// Output an closing </div> after duplicate widget content
add_action( 'c2c_after_duplicate_widget', 'my_c2c_after_duplicate_widget', 10, 2 );
function my_c2c_after_duplicate_widget( $instance, $args ) {
    echo '</div>;
}
</code></pre>
<h4>c2c_before_duplicate_widget_form (action)</h4>
<p>The ‘c2c_before_duplicate_widget_form’ hook allows you to output text, or perform some sort of action, just before the output of the duplicate widget’s configuration form (in the WP admin).</p>
<p>Arguments:</p>
<ul>
<li>$instance (array) : The settings for the widget instance (namely: title and widget_to_duplicate)</li>
</ul>
<p>Example:</p>
<pre><code>// Display a message just before the duplicate widget settings form
add_action( 'c2c_before_duplicate_widget_form', 'my_c2c_before_duplicate_widget_form' );
function my_c2c_before_duplicate_widget_form( $instance ) {
    echo '<p>Note: this is a note above the widget settings form.</p>';
}
</code></pre>
<h4>c2c_after_duplicate_widget_form (action)</h4>
<p>The ‘c2c_after_duplicate_widget_form’ hook allows you to output text, or perform some sort of action, just after the output of the duplicate widget’s configuration form (in the WP admin).</p>
<p>Arguments:</p>
<ul>
<li>$instance (array) : The settings for the widget instance (namely: title and widget_to_duplicate)</li>
</ul>
<p>Example:</p>
<pre><code>// Display a message just after the duplicate widget settings form
add_action( 'c2c_after_duplicate_widget_form', 'my_c2c_after_duplicate_widget_form' );
function my_c2c_after_duplicate_widget_form( $instance ) {
    echo '<p>Note: this is a note below the widget settings form.</p>';
}
</code></pre>


Duplicate Widget

A widget that can act as a duplicate of another widget (for synchronized use in another sidebar)

<p>Safely call a function, class method, or object method in a manner that doesn’t generate errors if those plugins cease to exist.</p>
<p>Various helper functions are provided that provide handy variations of this theme:</p>
<ul>
<li><code>_sfc()</code>: Safely call a function and get its return value</li>
<li><code>_sfce()</code>: Safely call a function and echo its return value</li>
<li><code>_sfcf()</code>: Safely call a function; if it doesn’t exist, then a fallback function (if specified) is called</li>
<li><code>_sfcm()</code>: Safely call a function; if it doesn’t exist, then echo a message (if provided)</li>
</ul>
<p>Let’s assume you had something like this in a template:</p>
<pre><code><?php list_cities( 'Texas', 3 ); ?>
</code></pre>
<p>If you deactivated the plugin that provided <code>list_cities()</code>, your site would generate an error when that template is accessed.</p>
<p>You can instead use <code>_sfc()</code>, which is provided by this plugin to call other functions, like so:</p>
<pre><code><?php _sfc( 'list_cities', 'Texas', 3 ); ?>
</code></pre>
<p>That will simply do nothing if the <code>list_cities()</code> function is not available.</p>
<p>If you’d rather display a message when the function does not exist, use <code>_sfcm()</code> instead, like so:</p>
<pre><code><?php _sfcm( 'list_cities', 'The cities listing is temporarily disabled.', 'Texas', 3 ); ?>
</code></pre>
<p>In this case, if <code>list_cities()</code> is not available, the text “The cities listing is temporarily disabled.” will be displayed.</p>
<p>If you’d rather call another function when the function does not exist, use _sfcf() instead, like so:</p>
<pre><code><?php
    function unavailable_function_handler( $function_name ) { echo "The function $function_name is not available."; }
    _sfcf( 'nonexistent_function', 'unavailable_function_handler' );
?>
</code></pre>
<p>In the event you want to safely call a function and echo its value, you can use <code>_sfce()</code> like so:</p>
<pre><code><?php _sfce( 'largest_city', 'Tx' ); ?>
</code></pre>
<p>Which is roughly equivalent to doing :</p>
<pre><code><?php if function_exists( 'largest_city' ) { echo largest_city( 'Tx' ); } ?>
</code></pre>
<h4>Filter invocation method</h4>
<p>To further prevent issues in your code should this plugin itself become deactivated, you can use indirect filter invocation to call the plugin functions. Each function has an associated filter with the same name as the function. Simply use <code>apply_filters()</code> to invoke that function instead of calling the function directly.</p>
<p>E.g. instead of:</p>
<pre><code><?php _sfce( 'some_plugin_function_that_echoes', 'argument' ); ?>
</code></pre>
<p>Do:</p>
<pre><code><?php apply_filters( '_sfce', 'some_plugin_function_that_echoes', 'argument' ); ?>
</code></pre>
<p>If you’re relying on the return value of a function and this plugin gets deactivated, note that the <code>apply_filters()</code> call will return the name of the function you intended to call, so you should check the return value to ensure the function got called.</p>
<p>Instead of:</p>
<pre><code><?php $x = _sfc( 'some_plugin_function', 'argument' ); ?>
</code></pre>
<p>Do:</p>
<pre><code><?php
    $x = apply_filters( '_sfcq', 'some_plugin_function', 'argument' );
    if ( $x !== 'some_plugin_function' ) {
        // Work with the value of $x here.
    } else {
        // The Safe Function Call plugin isn't active.
        $x = 0; // Maybe set the variable to something that makes sense in this scenario.
    }
?>
</code></pre>
<p>Links: <a href="https://coffee2code.com/wp-plugins/safe-function-call/" rel="nofollow ugc">Plugin Homepage</a> | <a href="https://wordpress.org/plugins/safe-function-call/" rel="ugc">Plugin Directory Page</a> | <a href="https://github.com/coffee2code/safe-function-call/" rel="nofollow ugc">GitHub</a> | <a href="https://coffee2code.com" rel="nofollow ugc">Author Homepage</a></p>
<h3>Developer Documentation</h3>
<p>Developer documentation can be found in <a href="https://github.com/coffee2code/safe-function-call/blob/master/DEVELOPER-DOCS.md" rel="nofollow ugc">DEVELOPER-DOCS.md</a>. That documentation covers the template tags and hooks provided by the plugin.</p>
<p>As an overview, these are the template tags provided by the plugin:</p>
<ul>
<li><code>_sfc()</code>  : Safely call a function and get its return value.</li>
<li><code>_sfce()</code> : Safely call a function and echo its sanitized return value.</li>
<li><code>_sfcf()</code> : Safely call a function; if it doesn’t exist, then a fallback function (if specified) is called.</li>
<li><code>_sfcm()</code> : Safely call a function; if it doesn’t exist, then echo a message (if provided).</li>
</ul>
<p>These are the hooks provided by the plugin. They are intended for filter invocation usage rather than typical content filtering.</p>
<ul>
<li><code>_sfc</code>  : Filter to safely invoke <code>_sfc()</code> in such a way that if the plugin were deactivated or deleted, then your calls to the function won’t cause errors in your site.</li>
<li><code>_sfce</code> : Filter to safely invoke <code>_sfce()</code> in such a way that if the plugin were deactivated or deleted, then your calls to the function won’t cause errors in your site.</li>
<li><code>_sfcf</code> : Filter to safely invoke <code>_sfcf()</code> in such a way that if the plugin were deactivated or deleted, then your calls to the function won’t cause errors in your site.</li>
<li><code>_sfcm</code> : Filter to safely invoke <code>_sfcm()</code> in such a way that if the plugin were deactivated or deleted, then your calls to the function won’t cause errors in your site.</li>
</ul>


Safe Function Call

Safely and easily call functions that may not be available (such as those provided by a plugin that gets deactivated)

Duplicate Widget vs Safe Function Call