Re: [FreeMarker-user] Evaluating Variables in Expressions

[Benjamin P. <be...@ga...>]

Daniel Dekany wrote:
> Thursday, September 16, 2004, 8:24:04 AM, Benjamin Podszun wrote:
> 
> [snip]
> 
>>Well, maybe it's really something dumb I'm doing in the macro.
> 
> 
> No mistake in the template should result in such low-lever error...
> 
> 
>>But this
>>macro and function cause a ConcurrentModificationError when called:
>>
>><#macro walk_tree currentHash>
>>        <#if currentHash?is_hash>
>>                <#list currentHash?keys as key>
>>                        <#if (currentHash[key])?if_exists>
> 
> 
> It's not the implementation you run, because that should use
> <#if (currentHash[key])?exists>.
> This mistake doesn't cause ConcurrentModificationError, of course...
> 
> 
>>                                <@walk_tree currentHash[key] />
>>                        </#if>
>>                </#list>
>>        </#if>
>></#macro>
>>
>><#function tree node>
>>        <#if node?is_hash>
>>                <#list node?keys as key>
>>                        ${key}
> 
> 
> This is again something strange. This function will always return "",
> because outputting operations in functions are disabled. Are you sure
> you have copy-pasted what you are using?

Yes, I pasted my "problem recipe", just to demonstrate/show that it 
happens inside functions as well as inside macros.
I worked around the problem by wrapping the data-structure in 
objects/classes with children in java.util.List ..
I'm still not sure why I hit this problem, though.

>>                        <#if node[key]?has_content>
>>                                ${tree(node[key])}
>>                        </#if>
>>                </#list>
>>        </#if>
>>
>>        <#return "">
>></#function>
>>
>>I call them with either
>><@walk_tree data.Menu.Structure />
>>or
>>${tree(data.Menu.Structure)}
>>
>>Yes, my FreeMarker version is 2.3 and I'm using the standard wrapper, 
>>that is I didn't change anything at all.
> 
> 
> I know it's annoying, but it still works for me! Both the macro and the
> function. I have built a 3 level depth tree from java.util.HashMap-s and
> traversed that with them. I have even put null value into it. Are you
> sure that data.Menu.Structure is only from HashMap-s? Is there a
> specific item where it stops with that error, or it dies on the very
> first item? And, really, what J2SE implementation are you using? Sun,
> IBM? Which version?
>

I'm using Sun's J2SE, version 1.4.2
The only "special" thing about my Hash might be that my Keys are (were 
-> workaround) objects (read: no Strings)?

> So... I think the solution will be if you write a *minimalist*
> stand-alone Java application that reproduces the problem. It's simple...
> just modify this, and create a template:

I'm trying to find/build a minimal recipe asap. Since I could work 
around this problem I've a little problem getting back on my 
timeline/roadmap ;)
So it might take me 1-2 days to try it again.

Thanks for the answer(s),
Ben