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  1. Velocity
  2. VELOCITY-186

#set does not allow to assign nulls---cannot it be changed?

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Details

    • Improvement
    • Status: Closed
    • Minor
    • Resolution: Fixed
    • 1.3.1
    • 1.5
    • Engine
    • None
    • Operating System: All
      Platform: All
    • 20999

    Description

      Currently #set does not change $ref if the value is null. To quote manual: "If
      the RHS evaluates to null, it is not assigned to the LHS". It has some
      advantages, but well, it has also disadvantages.

      In my concrete case, I have #foreach loop, where I list some items.
      Unfortunatley, the listing (I mean the output) heavily depends on values of
      some fields. Considering I have #foreach $item in $items I have to call
      $item.foo or $item.bar every time I need to check if the value is set or not.
      Instead I'd prefer to #set ($foo = $item.foo) a.s.o. and to use just $foo in
      further processing instead of calling $item getFoo() method all the time---
      it's not only about ease of writting, it's also about the time it takes to
      invoke that method, plus the time of what this metod really does (it's not
      always just simple return this.foo statement).

      Of course I would not like to break the compatibility of the #set behaviour,
      but I wonder if would be there a way to actually add the possibility to set
      some $ref to null, what would casue #if ($ref) to evaluate as false.

      Currently, using #set causes, that if we step on $item.foo that returns null,
      we have $ref set to the value of a previous $item. The workaround is to use
      $item.foo everywhere, but it's not very comfortable. Can it be done something
      about that? Maybe on option in velocity.properties enabling of returning nulls
      or new operator (instead of '=') to assign null values (like ':=' for example).

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            wglass William Glass-Husain
            t.kitynski@11interactive.com Tomislaw Kitynski
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            Dates

              Created:
              Updated:
              Resolved: