Hi list,
I have been using Velocity for quite a while and we have recently gone
to the 1.5 version (from a custom 1.4 version). We also have completely
refactored our code and our templates and we use velocity quite
intensively to generate code. We now have a model-driven code generation
that uses macros combined with #parse to generate our code.
Basically, I have one or several templates for each type of object of
our model, and I render each object by merging it with a template.
I have a macro that is call "render" to which I pass an object and the
macro is responsible to render that object. The macro knows which
template goes with which object and invoke the #parse() directive with
the proper template. This goes recursively until my whole object tree
has been parsed and rendered.
However, I found out recently that when you do a #set($something =
$null), if $something was declared in a higher template and $null is
undefined, $something will not take the null value but simply tries to
remove the reference from the vmproxyhash Hashmap. Although $something
may be defined in another context (for example the innerContext) and
therefore I obtain very strange behaviors because you expect something
to be null. This little snippet illustrates those strange behaviors:
## $something has been declared in another template (potentially the
same, since the way I use Velocity template is recursive)
#set($something = $myObject.getSomething()) ## getSomething() returns null
#if($something)
foo bar
...
#end
even if getSomething() returns null, $something won't be null and the
#if-block after will be rendered. This is of course unwanted and quite
hard to predict.
So far, the only solution I have found is to set the variable to false
before invoking the method, but I find it rather ugly.
IMHO, the method remove(Object) in VMContext should be similar to the
get/put methods. A cleaner way to do all this, should be a new property
that allows us to use or not chained-context.
Is there a way to bypass chained-context? or a way to set null values on
the contexts embedded by the VMContext? should I fill a bug report?
Thank in advance,
--
Guillaume Polet
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