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Home » Modeling » M2T (model-to-text transformation) » [Acceleo] Loop over empty OrderedSet creates empty lines(Or: How to ask if something != null)
[Acceleo] Loop over empty OrderedSet creates empty lines [message #1810144] Thu, 01 August 2019 10:43 Go to next message
Marie-Saphira Flug is currently offline Marie-Saphira FlugFriend
Messages: 7
Registered: January 2019
Junior Member
Hello,
I'm generating a .yaml file from an Xtext model and I have too many empty lines in it. In my template I print some properties that I get in an OrderedSet. During generation I get the following warning:
Invalid loop iteration at line 27 in Module generateDeployment for block for (aContainer.properties). Last recorded value of self was null.
in
[for (aProperty : Property | aContainer.properties)]
    [aProperty.printProperties()/]
[/for]

'aContainer.properties' is the OrderedSet, which is null sometimes. I'm pretty sure that this triggers the warning.
I would like to use "!= null" or "!oclIsUndefined" but I can't find a "not" operation anywhere.
I know that I can remove the empty lines in a post process, but I really don't want the warnings because the user will see them.

Thanks in advance,
Saphira

EDIT:
so (something <> null) is working, I put it in front of every loop. Is there maybe a better way?

[Updated on: Thu, 01 August 2019 10:59]

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Re: [Acceleo] Loop over empty OrderedSet creates empty lines [message #1810155 is a reply to message #1810144] Thu, 01 August 2019 15:49 Go to previous message
Ed Willink is currently offline Ed WillinkFriend
Messages: 6534
Registered: July 2009
Senior Member
Hi

There are surely many different ways. Which is 'better' would require analysis of more of your code. However using a not-null guard to protect against null usage is a pretty standard idiom in many languages, so I suspect most alternatives would just be obscure.

Regards

Ed Willink
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