Introduce require_if_theme_supports(), move post thumbnails functions to there own include and only included them if the theme supports them. See #10928 and [12132]

git-svn-id: http://svn.automattic.com/wordpress/trunk@12134 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/post-image-template.php

@@ -0,0 +1,43 @@
+<?php
+/**
+ * WordPress Post Image Template Functions.
+ *
+ * Support for post thumbnails
+ * Themes function.php must call add_theme_support( 'post-thumbnails' ) to use these.
+ *
+ * @package WordPress
+ * @subpackage Template
+ */
+
+function has_post_image( $post_id = NULL ) {
+	global $id;
+	$post_id = ( NULL === $post_id ) ? $id : $post_id;
+	return !! get_post_image_id( $post_id );
+}
+
+function get_post_image_id( $post_id = NULL ) {
+	global $id;
+	$post_id = ( NULL === $post_id ) ? $id : $post_id;
+	return get_post_meta( $post_id, '_thumbnail_id', true );
+}
+
+function the_post_image( $size = 'thumbnail', $attr = '' ) {
+	echo get_the_post_image( NULL, $size, $attr );
+}
+
+function get_the_post_image( $post_id = NULL, $size = 'thumbnail', $attr = '' ) {
+	global $id;
+	$post_id = ( NULL === $post_id ) ? $id : $post_id;
+	$post_image_id = get_post_image_id( $post_id );
+	$size = apply_filters( 'post_image_size', $size );
+	if ( $post_image_id ) {
+		do_action( 'begin_fetch_post_image_html', $post_id, $post_image_id, $size ); // for "Just In Time" filtering of all of wp_get_attachment_image()'s filters
+		$html = wp_get_attachment_image( $post_image_id, $size, false, $attr );
+		do_action( 'end_fetch_post_image_html', $post_id, $post_image_id, $size );
+	} else {
+		$html = '';
+	}
+	return apply_filters( 'post_image_html', $html, $post_id, $post_image_id );
+}
+
+?>

wp-includes/post-template.php

@@ -880,41 +880,6 @@ function walk_page_dropdown_tree() {
 	return call_user_func_array(array(&$walker, 'walk'), $args);
 }
 
-//
-// Post images
-//
-
-function has_post_image( $post_id = NULL ) {
-	global $id;
-	$post_id = ( NULL === $post_id ) ? $id : $post_id;
-	return !! get_post_image_id( $post_id );
-}
-
-function get_post_image_id( $post_id = NULL ) {
-	global $id;
-	$post_id = ( NULL === $post_id ) ? $id : $post_id;
-	return get_post_meta( $post_id, '_thumbnail_id', true );
-}
-
-function the_post_image( $size = 'thumbnail', $attr = '' ) {
-	echo get_the_post_image( NULL, $size, $attr );
-}
-
-function get_the_post_image( $post_id = NULL, $size = 'thumbnail', $attr = '' ) {
-	global $id;
-	$post_id = ( NULL === $post_id ) ? $id : $post_id;
-	$post_image_id = get_post_image_id( $post_id );
-	$size = apply_filters( 'post_image_size', $size );
-	if ( $post_image_id ) {
-		do_action( 'begin_fetch_post_image_html', $post_id, $post_image_id, $size ); // for "Just In Time" filtering of all of wp_get_attachment_image()'s filters
-		$html = wp_get_attachment_image( $post_image_id, $size, false, $attr );
-		do_action( 'end_fetch_post_image_html', $post_id, $post_image_id, $size );
-	} else {
-		$html = '';
-	}
-	return apply_filters( 'post_image_html', $html, $post_id, $post_image_id );
-}
-
 //
 // Attachments
 //

wp-includes/theme.php

@@ -1305,6 +1305,8 @@ function add_custom_image_header($header_callback, $admin_header_callback) {
 
 /**
  * Allows a theme to register its support of a certain feature
+ * 
+ * Must be called in the themes functions.php file to work.
  *
  * @author Mark Jaquith
  * @since 2.9
@@ -1329,4 +1331,17 @@ function current_theme_supports( $feature ) {
 	return ( isset( $_wp_theme_features[$feature] ) && $_wp_theme_features[$feature] );
 }
 
+/**
+ * Checks a theme's support for a given feature before loading the functions which implement it.
+ *
+ * @author Peter Westwood
+ * @since 2.9
+ * @param string $feature the feature being checked
+ * @param string $include the file containing the functions that implement the feature
+ */
+function require_if_theme_supports( $feature, $include) {
+	if ( current_theme_supports( $feature ) )
+		require ( $include );
+}
+
 ?>

wp-settings.php

@@ -687,6 +687,9 @@ if ( TEMPLATEPATH !== STYLESHEETPATH && file_exists(STYLESHEETPATH . '/functions
 if ( file_exists(TEMPLATEPATH . '/functions.php') )
 	include(TEMPLATEPATH . '/functions.php');
 
+// Load in support for template functions which the theme supports
+require_if_theme_supports( 'post-thumbnails', ABSPATH . WPINC . '/post-image-template.php' );
+
 /**
  * Runs just before PHP shuts down execution.
  *