VTL evaluate or define an object reference
I would like to create a macro that takes a string as a parameter and evaluates that to an object. Something like:
#macro( valueTest $objRef)
#define( $obj )#evaluate("$${objRef}")#end
$obj.foo ## This would have to be translated to $obj.getFoo()
#end
Unfortunately the $obj variable does not point to object reference that could be used to call methods. $obj is a String and $obj.foo does not try to execute getFoo.
Somewhy I have a feeling that this is the nature of evaluate and it is not possible to do what I want to.
the reason why I want to do smth like this is because we have quite few macros that take both command bind path and command itself as a parameter and I am hoping the latter could be derived 开发者_StackOverflowfrom first.
Unfortunately, Velocity does not have a mechanism to define functions which return object references. Macros are really intended to be a shortcut to display text.
In cases like this, the way to proceed is generally to create a "tool" in Java and put an instance in the context. A tool is just an ordinary class with a method that returns what you are looking for
e.g.
create an object with an "eval" method, then put it in the context as "referenceEvaluator".
#set($obj = $referenceEvaluator.eval($objRef))
You might find that your code is clearer if you avoid the double evaluation and just insert an object into the context named $obj that does what you want. (better performance, too).
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