[FREEMARKER-24] Support of default methods in object model

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.3.24-incubating
• Fix Version/s: 2.3.26-incubating
• Component/s: engine
• Assignee: Dániel Dékány
• Reporter: Emmanuel Keller
• Created: 17/May/16 10:11
• Updated: 26/Mar/17 19:01
• Resolved: 10/Mar/17 23:38

Description

The default object method model currently does not support default methods:
https://docs.oracle.com/javase/tutorial/java/IandI/defaultmethods.html

Here is the current error:

FTL stack trace ("~" means nesting-related):
	- Failed at: #if task.switchable  [in template "...../home.ftl" at line 43, column 25]
----
	at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:131)
	at freemarker.core.UnexpectedTypeException.newDesciptionBuilder(UnexpectedTypeException.java:77)
	at freemarker.core.UnexpectedTypeException.<init>(UnexpectedTypeException.java:40)
	at freemarker.core.NonBooleanException.<init>(NonBooleanException.java:44)
	at freemarker.core.Expression.modelToBoolean(Expression.java:142)
	at freemarker.core.Expression.evalToBoolean(Expression.java:125)
	at freemarker.core.Expression.evalToBoolean(Expression.java:110)
	at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:46)
	at freemarker.core.Environment.visit(Environment.java:324)
	at freemarker.core.MixedContent.accept(MixedContent.java:54)
	at freemarker.core.Environment.visitByHiddingParent(Environment.java:345)
	at freemarker.core.IteratorBlock$IterationContext.executeNestedBlockInner(IteratorBlock.java:240)
	at freemarker.core.IteratorBlock$IterationContext.executeNestedBlock(IteratorBlock.java:220)
	at freemarker.core.IteratorBlock$IterationContext.accept(IteratorBlock.java:194)
	at freemarker.core.Environment.visitIteratorBlock(Environment.java:572)
	at freemarker.core.IteratorBlock.acceptWithResult(IteratorBlock.java:78)
	at freemarker.core.IteratorBlock.accept(IteratorBlock.java:64)
	at freemarker.core.Environment.visit(Environment.java:324)
	at freemarker.core.MixedContent.accept(MixedContent.java:54)
	at freemarker.core.Environment.visit(Environment.java:324)
	at freemarker.core.Environment.process(Environment.java:302)
	at freemarker.template.Template.process(Template.java:325)
	at com.qwazr.tools.FreeMarkerTool.template(FreeMarkerTool.java:86)
	at com.qwazr.tools.FreeMarkerTool.template(FreeMarkerTool.java:101)

To reproduce this.

1. Use an interface

public interface UpdatableTask extends Runnable {

    default boolean isSwitchable() {
        return false;
    }
}

2. Use an object that implements this interface with the following template:

<#if task.switchable>
...
</#if>