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https://issues.apache.org/jira/browse/VELOCITY-892?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16650084#comment-16650084
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Thomas Mortagne edited comment on VELOCITY-892 at 10/15/18 11:16 AM:
---------------------------------------------------------------------

I'm not really talking about having two methods in the same class but simply 
having methods taking something else than List<String> or List as parameter.

Imagine the following use case:

{code}
    public void foo(List<Integer> parameter)
    {
        for (Integer value : parameter) {
            // do stuff with the integer
        }
    }
{code}

{code}
$obj.foo("1, 2, 3, 4, 5")
{code}

It's impossible for the converter to know it should convert each element of the 
list to Integer so at best you will write a converter which produce a 
List<String> and the method will crash with a ClassCastException.


was (Author: tmortagne):
I'm not really talking about having two methods in the same class but simply 
having methods taking something else than List<String> or List as parameter.

Imagine the following use case:

{quote}
    public void foo(List<Integer> parameter)
    {
        for (Integer value : parameter) {
            // do stuff with the integer
        }
    }
{quote}

{quote}
$obj.foo("1, 2, 3, 4, 5")
{quote}

It's impossible for the converter to know it should convert each element of the 
list to Integer so at best you will write a converter which produce a 
List<String> and the method will crash with a ClassCastException.

> Method arguments conversions should be based on Type instead of Class
> ---------------------------------------------------------------------
>
>                 Key: VELOCITY-892
>                 URL: https://issues.apache.org/jira/browse/VELOCITY-892
>             Project: Velocity
>          Issue Type: Improvement
>          Components: Engine
>    Affects Versions: 2.0
>            Reporter: Thomas Mortagne
>            Priority: Major
>             Fix For: 2.0
>
>
> I was happy to see that method arguments conversion has been added to 2.0 so 
> that I can remove the uberspector we have on XWiki side but unfortunately 
> ConversionHandler is limited to classes which is way too restrictive for us 
> (for example if the parameter type is List<String> it won't do the same thing 
> than if the type is List<Integer>).
> Our uberspector can be found on 
> https://github.com/xwiki/xwiki-commons/blob/master/xwiki-commons-core/xwiki-commons-velocity/src/main/java/org/xwiki/velocity/introspection/MethodArgumentsUberspector.java
>  to see what we do exactly.



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