svn commit: r1040166 - in /ant/core/trunk/docs/manual/Tasks: taskdef.html typedef.html

[bodewig]

Author: bodewig
Date: Mon Nov 29 16:06:11 2010
New Revision: 1040166

URL: http://svn.apache.org/viewvc?rev=1040166&view=rev
Log:
Try to be more explicit about classloaders and their impact on typedef/taskdef

Modified:
    ant/core/trunk/docs/manual/Tasks/taskdef.html
    ant/core/trunk/docs/manual/Tasks/typedef.html

Modified: ant/core/trunk/docs/manual/Tasks/taskdef.html
URL: 
http://svn.apache.org/viewvc/ant/core/trunk/docs/manual/Tasks/taskdef.html?rev=1040166&r1=1040165&r2=1040166&view=diff
==============================================================================
--- ant/core/trunk/docs/manual/Tasks/taskdef.html (original)
+++ ant/core/trunk/docs/manual/Tasks/taskdef.html Mon Nov 29 16:06:11 2010
@@ -31,7 +31,8 @@
   <p>This task is a form of <a href="typedef.html">Typedef</a> with the
     attributes "adapter" and "adaptto" set to the values 
     "org.apache.tools.ant.TaskAdapter" and "org.apache.tools.ant.Task"
-    respectively.
+    respectively.  Anything said in the <a href="typedef.html">manual
+      page of typedef</a> applies to taskdef as well.</p>
 <h3>Examples</h3>
 <pre>  &lt;taskdef name=&quot;myjavadoc&quot; 
classname=&quot;com.mydomain.JavadocTask&quot;/&gt;</pre>
 <p>makes a task called <code>myjavadoc</code> available to Apache Ant. The 
class <code>com.mydomain.JavadocTask</code>

Modified: ant/core/trunk/docs/manual/Tasks/typedef.html
URL: 
http://svn.apache.org/viewvc/ant/core/trunk/docs/manual/Tasks/typedef.html?rev=1040166&r1=1040165&r2=1040166&view=diff
==============================================================================
--- ant/core/trunk/docs/manual/Tasks/typedef.html (original)
+++ ant/core/trunk/docs/manual/Tasks/typedef.html Mon Nov 29 16:06:11 2010
@@ -62,6 +62,27 @@
     <a href="../Types/antlib.html">Antlib</a> section.
   </p>
 
+  <p>If you are defining tasks or types that share the same classpath
+    with multiple taskdef or typedef tasks, the corresponding classes
+    will be loaded by different
+    Java <a 
href="http://download.oracle.com/javase/1.4.2/docs/api/java/lang/ClassLoader.html";>ClassLoaders</a>.
+    Two classes with the same name loaded via different ClassLoaders
+    are not the same class from the point of view of the Java VM, they
+    don't share static variables and instances of these classes can't
+    access private methods or attributes of instances defined by "the
+    other class" of the same name.  They don't even belong to the same
+    Java package and can't access package private code, either.</p>
+
+  <p>The best way to load several tasks/types that are supposed to
+    cooperate with each other via shared Java code is to use the
+    resource attribute and an antlib descriptor.  If this is not
+    possible, the second best option is to use the loaderref attribute
+    and specify the same name for each and every typedef/taskdef -
+    this way the classes will share the same ClassLoader.  Note that
+    the typedef/taskdef tasks must use identical classpath defintions
+    (this includes the order of path components) for the loaderref
+    attribute to work.</p>
+
 <h3>Parameters</h3>
 <table border="1" cellpadding="2" cellspacing="0">
   <tr>