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 <h1 class="content-header header-section1" id="pgui_config_incompatible_improvements" itemprop="headline">The &quot;incompatible improvements&quot; setting</h1>
 </div></div><div class="page-menu">
 <div class="page-menu-title">Page Contents</div>
 <ul><li><a class="page-menu-link" href="#autoid_51" data-menu-target="autoid_51">What does it do</a></li><li><a class="page-menu-link" href="#pgui_config_incompatible_improvements_how_to_set" data-menu-target="pgui_config_incompatible_improvements_how_to_set">How to set it</a></li></ul> </div>


 <h2 class="content-header header-section2" id="autoid_51">What does it do</h2>


           <p>This setting specifies the FreeMarker version number where the
           not 100% backward compatible bug fixes and improvements
           <em>that you want to enable</em> were already
           implemented. Usually, it&#39;s a bad idea to left it on its default,
           which is 2.3.0 (maximum backward compatibility).</p>

           <p>In new projects you should set this to the fixed FreeMarker
           version (like <code class="inline-code">Configuration.VERSION_2_3_28</code>) that
           you are actually using when starting the project. In older projects
           it&#39;s also usually better to keep this high , however you should
           check the changes activated (find them in <a href="https://freemarker.apache.org/docs/api/freemarker/template/Configuration.html#Configuration-freemarker.template.Version-">the
           API JavaDoc of the <code>Configuration(Version)</code>
           constructor</a>), especially if not only the 3rd version number
           (the micro version) of "incompatible improvements"
           setting is increased. Generally, as far as you only increase the
           last (3rd) version number of this setting, the changes are low risk,
           and whether you can afford that risk depends on the concrete
           application. Never use a dynamic value like
           <code class="inline-code">Configuration.getVersion()</code> though, as that way
           upgrading FreeMarker can break your application!</p>

           <p>Bug fixes and improvements that are fully backward compatible,
           also those that are important security fixes, are enabled regardless
           of the "incompatible improvements" setting.</p>

           <p>An important consequence of setting this setting is that now
           your application will check if the stated minimum FreeMarker version
           requirement is met. Like if you set this setting to 2.3.22, but
           accidentally the application is deployed with FreeMarker 2.3.21,
           then FreeMarker will fail, telling that a higher version is
           required. After all, the fixes/improvements you have requested
           aren&#39;t available on a lower version.</p>


 <h2 class="content-header header-section2" id="pgui_config_incompatible_improvements_how_to_set">How to set it</h2>


           <p>The incompatible improvements setting exists on the
           <code class="inline-code">Configuration</code> level. It can be set on multiple
           ways:</p>

           <ul>
             <li>
               <p>Create the
               <code class="inline-code">freemarker.template.Configuration</code> object
               like:</p>


     <div class="code-block role-unspecified">
 <pre class="code-block-body">... = new Configuration(Configuration.VERSION_2_3_28)</pre>    </div>

             </li>

             <li>
               <p>Or, alter the <code class="inline-code">Configuration</code> singleton
               where you initialize its other settings like:</p>


     <div class="code-block role-unspecified">
 <pre class="code-block-body">cfg.setIncompatibleImprovements(Configuration.VERSION_2_3_28)</pre>    </div>

             </li>

             <li>
               <p>Or, if you are configuring FreeMarker with properties
               (<code class="inline-code">*.properties</code> file or
               <code class="inline-code">java.util.Properties</code> object), add:</p>


     <div class="code-block role-unspecified">
 <pre class="code-block-body">incompatible_improvements=2.3.28</pre>    </div>

             </li>

             <li>
               <p>Or, if you are configuring FreeMarker through
               <code class="inline-code">FreemarkerServlet</code>, add this
               <code class="inline-code">init-param</code> to it in the
               <code class="inline-code">web.xml</code>:</p>


     <div class="code-block role-unspecified">
 <pre class="code-block-body">&lt;init-param&gt;
     &lt;param-name&gt;incompatible_improvements&lt;/param-name&gt;
     &lt;param-value&gt;2.3.28&lt;/param-value&gt;
 &lt;/init-param&gt;</pre>    </div>

             </li>
           </ul>

           <p>But, <em>if you set the
           <code class="inline-code">object_wrapper</code> setting</em> (same as
           <code class="inline-code">Configuration.setObjectWrapper(ObjectWrapper)</code>) of
           your configuration, then it&#39;s important to know that
           <code class="inline-code">BeansWrapper</code> and its subclasses (most
           importantly, <code class="inline-code">DefaultObjectWrapper</code>) has its own
           independent <code class="inline-code">incompatibleImprovements</code> property,
           and some fixes/improvements are activated by that, not by
           <code class="inline-code">Configuration</code>&#39;s similar setting. You don&#39;t have
           to be aware of this complication if you aren&#39;t setting the
           <code class="inline-code">object_wrapper</code> configuration setting anywhere,
           because the default <code class="inline-code">object_wrapper</code> has the same
           "incompatible improvements" as of the
           <code class="inline-code">Configuration</code>. But if you are setting the
           <code class="inline-code">object_wrapper</code>, then you must not forget to set
           the <code class="inline-code">incompatibleImprovements</code> property of the
           <code class="inline-code">ObjectWrapper</code> itself, in additionally to that of
           the <code class="inline-code">Configuration</code>. (Note that it&#39;s fine to have
           different "incompatible improvements" for the
           <code class="inline-code">Configuration</code> and for the
           <code class="inline-code">ObjectWrapper</code>, only it should be a conscious
           decision.) <a href="pgui_datamodel_objectWrapper.html#topic.setDefaultObjectWrapperIcIIndividually">See here how
           to set it</a> in the case of
           <code class="inline-code">DefaultObjectWrapper</code> (for
           <code class="inline-code">BeansWrapper</code> it&#39;s the same, only with different
           class name of course).</p>

             <div class="callout warning">
     <strong class="callout-label">Warning!</strong>

             <p>Do not ever use
             <code class="inline-code">Configuration.getVersion()</code> to set the
             "incompatible improvements" setting. Always use a
             fixed value, like <code class="inline-code">Configuration.VERSION_2_3_28</code>.
             Otherwise your application can break as you upgrade FreeMarker.
             The whole point of "incompatible improvements" is to
             protect you from that, while you still always get the
             fixes/improvements that are backward compatible.</p>
             </div>

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	<h1 class="content-header header-section1" id="pgui_config_incompatible_improvements" itemprop="headline">The "incompatible improvements" setting</h1>
	</div></div><div class="page-menu">
	<div class="page-menu-title">Page Contents</div>
	<ul><li><a class="page-menu-link" href="#autoid_51" data-menu-target="autoid_51">What does it do</a></li><li><a class="page-menu-link" href="#pgui_config_incompatible_improvements_how_to_set" data-menu-target="pgui_config_incompatible_improvements_how_to_set">How to set it</a></li></ul> </div>




	<h2 class="content-header header-section2" id="autoid_51">What does it do</h2>


	<p>This setting specifies the FreeMarker version number where the
	not 100% backward compatible bug fixes and improvements
	<em>that you want to enable</em> were already
	implemented. Usually, it's a bad idea to left it on its default,
	which is 2.3.0 (maximum backward compatibility).</p>

	<p>In new projects you should set this to the fixed FreeMarker
	version (like <code class="inline-code">Configuration.VERSION_2_3_28</code>) that
	you are actually using when starting the project. In older projects
	it's also usually better to keep this high , however you should
	check the changes activated (find them in <a href="https://freemarker.apache.org/docs/api/freemarker/template/Configuration.html#Configuration-freemarker.template.Version-">the
	API JavaDoc of the <code>Configuration(Version)</code>
	constructor</a>), especially if not only the 3rd version number
	(the micro version) of "incompatible improvements"
	setting is increased. Generally, as far as you only increase the
	last (3rd) version number of this setting, the changes are low risk,
	and whether you can afford that risk depends on the concrete
	application. Never use a dynamic value like
	<code class="inline-code">Configuration.getVersion()</code> though, as that way
	upgrading FreeMarker can break your application!</p>

	<p>Bug fixes and improvements that are fully backward compatible,
	also those that are important security fixes, are enabled regardless
	of the "incompatible improvements" setting.</p>

	<p>An important consequence of setting this setting is that now
	your application will check if the stated minimum FreeMarker version
	requirement is met. Like if you set this setting to 2.3.22, but
	accidentally the application is deployed with FreeMarker 2.3.21,
	then FreeMarker will fail, telling that a higher version is
	required. After all, the fixes/improvements you have requested
	aren't available on a lower version.</p>





	<h2 class="content-header header-section2" id="pgui_config_incompatible_improvements_how_to_set">How to set it</h2>


	<p>The incompatible improvements setting exists on the
	<code class="inline-code">Configuration</code> level. It can be set on multiple
	ways:</p>

	<ul>
	<li>
	<p>Create the
	<code class="inline-code">freemarker.template.Configuration</code> object
	like:</p>



	<div class="code-block role-unspecified">
	<pre class="code-block-body">... = new Configuration(Configuration.VERSION_2_3_28)</pre> </div>

	</li>

	<li>
	<p>Or, alter the <code class="inline-code">Configuration</code> singleton
	where you initialize its other settings like:</p>



	<div class="code-block role-unspecified">
	<pre class="code-block-body">cfg.setIncompatibleImprovements(Configuration.VERSION_2_3_28)</pre> </div>

	</li>

	<li>
	<p>Or, if you are configuring FreeMarker with properties
	(<code class="inline-code">*.properties</code> file or
	<code class="inline-code">java.util.Properties</code> object), add:</p>



	<div class="code-block role-unspecified">
	<pre class="code-block-body">incompatible_improvements=2.3.28</pre> </div>

	</li>

	<li>
	<p>Or, if you are configuring FreeMarker through
	<code class="inline-code">FreemarkerServlet</code>, add this
	<code class="inline-code">init-param</code> to it in the
	<code class="inline-code">web.xml</code>:</p>



	<div class="code-block role-unspecified">
	<pre class="code-block-body"><init-param>
	<param-name>incompatible_improvements</param-name>
	<param-value>2.3.28</param-value>
	</init-param></pre> </div>

	</li>
	</ul>

	<p>But, <em>if you set the
	<code class="inline-code">object_wrapper</code> setting</em> (same as
	<code class="inline-code">Configuration.setObjectWrapper(ObjectWrapper)</code>) of
	your configuration, then it's important to know that
	<code class="inline-code">BeansWrapper</code> and its subclasses (most
	importantly, <code class="inline-code">DefaultObjectWrapper</code>) has its own
	independent <code class="inline-code">incompatibleImprovements</code> property,
	and some fixes/improvements are activated by that, not by
	<code class="inline-code">Configuration</code>'s similar setting. You don't have
	to be aware of this complication if you aren't setting the
	<code class="inline-code">object_wrapper</code> configuration setting anywhere,
	because the default <code class="inline-code">object_wrapper</code> has the same
	"incompatible improvements" as of the
	<code class="inline-code">Configuration</code>. But if you are setting the
	<code class="inline-code">object_wrapper</code>, then you must not forget to set
	the <code class="inline-code">incompatibleImprovements</code> property of the
	<code class="inline-code">ObjectWrapper</code> itself, in additionally to that of
	the <code class="inline-code">Configuration</code>. (Note that it's fine to have
	different "incompatible improvements" for the
	<code class="inline-code">Configuration</code> and for the
	<code class="inline-code">ObjectWrapper</code>, only it should be a conscious
	decision.) <a href="pgui_datamodel_objectWrapper.html#topic.setDefaultObjectWrapperIcIIndividually">See here how
	to set it</a> in the case of
	<code class="inline-code">DefaultObjectWrapper</code> (for
	<code class="inline-code">BeansWrapper</code> it's the same, only with different
	class name of course).</p>

	<div class="callout warning">
	<strong class="callout-label">Warning!</strong>

	<p>Do not ever use
	<code class="inline-code">Configuration.getVersion()</code> to set the
	"incompatible improvements" setting. Always use a
	fixed value, like <code class="inline-code">Configuration.VERSION_2_3_28</code>.
	Otherwise your application can break as you upgrade FreeMarker.
	The whole point of "incompatible improvements" is to
	protect you from that, while you still always get the
	fixes/improvements that are backward compatible.</p>
	</div>

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