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https://issues.apache.org/jira/browse/JEXL-224?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16059241#comment-16059241
]
Dmitri Blinov commented on JEXL-224:
------------------------------------
I have managed to achieve what I whanted by overriding
{{Uberspect.getMethod()}} and implementing custom JexlMethod class
{code}
protected class CollectionJexlMethod implements JexlMethod {
public CollectionJexlMethod() {
}
@Override
public Object invoke(Object obj, Object... params) throws Exception {
if (obj instanceof Collection && params != null && params.length == 1)
{
Collection c = (Collection) obj;
int i = TypeCast.getInt(params[0]);
for (Object o : c) {
if (i-- == 0)
return o;
}
}
return null;
}
@Override
public Object tryInvoke(String name, Object obj, Object... params) {
if (obj instanceof Collection && "call".equals(name) && params != null
&& params.length == 1) {
Collection c = (Collection) obj;
int i = TypeCast.getInt(params[0]);
for (Object o : c) {
if (i-- == 0)
return o;
}
}
return JexlEngine.TRY_FAILED;
}
@Override
public boolean tryFailed(Object rval) {
return rval == JexlEngine.TRY_FAILED;
}
@Override
public boolean isCacheable() {
return true;
}
@Override
public Class<?> getReturnType() {
return Object.class;
}
}
@Override
public JexlMethod getMethod(Object obj, String method, Object... args) {
JexlMethod result = super.getMethod(obj, method, args);
if (result == null) {
if (obj instanceof Collection && "call".equals(method) && args != null
&& args.length == 1) {
result = new CollectionJexlMethod();
}
}
return result;
}
{code}
The code is not as eloquent as it would be with JEXL-224 implemented, but it
seems to work and I don't know if the issue is still worth fixing
> The ability to overload call() operator in customized JexlArithmetic
> implementation
> -----------------------------------------------------------------------------------
>
> Key: JEXL-224
> URL: https://issues.apache.org/jira/browse/JEXL-224
> Project: Commons JEXL
> Issue Type: Improvement
> Affects Versions: 3.1
> Reporter: Dmitri Blinov
> Priority: Minor
>
> As of now there is a possibility to overload some operators and property
> accessors in JexlArithmetic, such as {{[]}}, {{.}} and {{~=}}, which is great
> extension point of Jexl. Suppose I want to implement index-based access to a
> {{j.u.Collection}} instance in a manner that {{a(0)}} would return the first
> element of collection, {{a(1)}} would return the second and so forth. This is
> different from using common access operator {{[]}} in a way that I specify
> not the index key of for example ArrayList, but an ordered index of the
> element. Of course, the is a possibility to introduce some function to this,
> but for the sake of the scripting simplicity I'm looking for the short
> version, like the call operator {{()}}. As of now I can only implement this
> behavior for the classes that are written by me, via adding a call() method
> to class declaration.But in the case of java.util.Collection this is not
> possible. So it would be great if Jexl could allow to overload a call()
> method in JexlArithmetic class in a way the propertyGet/arrayGet methods are
> now can be overloaded.
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