Wrapper functions for Advanced Custom Fields

acf-wrapper-functions.php

<?php
/**
 * Return a custom field stored by the Advanced Custom Fields plugin
 * 
 * @global $post
 * @param str $key The key to look for
 * @param mixed $id The post ID (int|str, defaults to $post->ID)
 * @param mixed $default Value to return if get_field() returns nothing
 * @return mixed
 * @uses get_field()
 */
function _get_field( $key, $id=false, $default='' ) {
  global $post;
  $key = trim( filter_var( $key, FILTER_SANITIZE_STRING ) );
  $result = '';
 
  if ( function_exists( 'get_field' ) ) {
    if ( isset( $post->ID ) && !$id )
      $result = get_field( $key );
    else
      $result = get_field( $key, $id );
 
    if ( $result == '' ) // If ACF enabled but key is undefined, return default
      $result = $default;
 
  } else {
    $result = $default;
  }

  return $result;
}

/**
 * Shortcut for 'echo _get_field()'
 * @param str $key The meta key
 * @param mixed $id The post ID (int|str, defaults to $post->ID)
 * @param mixed $default Value to return if there's no value for the custom field $key
 * @return void
 * @uses _get_field()
 */
function _the_field( $key, $id=false, $default='' ) {
  echo _get_field( $key, $id, $default );
}

/**
 * Get a sub field of a Repeater field
 * @param str $key The meta key
 * @param mixed $default Value to return if there's no value for the custom field $key
 * @return mixed
 * @uses get_sub_field()
 */
function _get_sub_field( $key, $default='' ) {
   if ( function_exists( 'get_sub_field' ) &&  get_sub_field( $key ) )  
    return get_sub_field( $key );
   else 
    return $default;
}

/**
 * Shortcut for 'echo _get_sub_field()'
 * @param str $key The meta key Value to return if there's no value for the custom field $key
 * @return void
 * @uses _get_sub_field()
 */
function _the_sub_field( $key, $default='' ) {
  echo _get_sub_field( $key, $default );
}

/**
 * Check if a given field has a sub field
 * @param str $key The meta key
 * @param mixed $id The post ID
 * @return bool
 * @uses has_sub_field()
 */
function _has_sub_field( $key, $id=false ) {
  if ( function_exists('has_sub_field') )
    return has_sub_field( $key, $id );
  else
    return false;
}

using.php

<?php
# For example using "_the field" function like one of the following:

echo _the_field( 'custom_field_key_goes_here', 123, 'This is the default content that will be displayed if nothing returns for the field' );

return _the_field( 'custom_field_key_goes_here', 123, 'This is the default content that will be displayed if nothing returns for the field' );

#Pretty cool. My php isn't great though... can you tell me if this is the correct way to use them?

#For example using "_the field" function like one of the following:

echo _the_field( 'custom_field_key_goes_here', 123, 'This is the default content that will be displayed if nothing returns for the field' );

return _the_field( 'custom_field_key_goes_here', 123, 'This is the default content that will be displayed if nothing returns for the field' );

#Also it looks like the shortcut functions are used basically just to avoid writing echo... Would doing something like the following make it even simpler by integrating echo/return directly into the functions instead of createding additional functions/shortcuts?

function _get_field( $key, $id=false, $default='', $echo = FALSE ) {
global $post;
$key = trim( filter_var( $key, FILTER_SANITIZE_STRING ) );
$result = '';

if ( function_exists( 'get_field' ) ) {
if ( isset( $post->ID ) && !$id )
$result = get_field( $key );
else

?>