return undefined;

Conditional selections based on sibling values in E4X

Posted in AS3, Flash by Ben Clinkinbeard on the August 18th, 2006

This may be obvious to others but I found it a bit counter intuitive and thought I would post a note as much for my own reference as for others. Consider the following code:

PLAIN TEXT
Actionscript:
  1. var x:XML =
  2. <Plans>
  3.     <Plan>
  4.         <Industry>MFG</Industry>
  5.         <Contact>Bob Cratchett</Contact>
  6.         <PlanNumber>11111</PlanNumber>
  7.     </Plan>
  8.     <Plan>
  9.         <Industry>AEROSPACE</Industry>
  10.         <Contact>Bo Peep</Contact>
  11.         <PlanNumber>22222</PlanNumber>
  12.     </Plan>
  13.     <Plan>
  14.         <Industry>ENTERTAINMENT</Industry>
  15.         <Contact>Scrooge McDuck</Contact>
  16.         <PlanNumber>33333</PlanNumber>
  17.     </Plan>
  18. </Plans>;
  19.  
  20. trace(x.Plan.(Industry == "AEROSPACE").PlanNumber);

This will return the correct value (22222), but I thought it was a bit odd that the dot that precedes the condition does not actually take you down into the node, allowing you to still directly access the property you're after. I think this is a very smart implementation because otherwise it would be very difficult and convoluted to select a value based on a sibling value. It would likely require something similar to, albeit more complicated than, the methodology recently discussed by Mike Chambers.

E4X definitely rocks the house.

2 Responses to 'Conditional selections based on sibling values in E4X'

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  1. Robert Penner said,

    on August 18th, 2006 at 7:55 pm

    That may be because x.Plan is an XMLList, and (Industry == "AEROSPACE") is selecting one Plan in the list.

  2. Ben said,

    on August 18th, 2006 at 8:52 pm

    Good point Robert. I guess it is a little more straightforward than I thought. Like I said, E4X rocks :)

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