Description Jesper Moller 2011-06-18 19:33:25 EDT

Note: This is from RC3, I think, but I couldn't find this in Bugzilla, and it doesn't look like it's fixes in Git.

--

First, I found what I thought to be a bug in Xtend2:

class LoopVarFinal {
			
	def problem_1() ''' 
		«FOR i:1..10»
			«FOR j:(1..10).map(k | k*i) SEPARATOR " ... "»«j»«ENDFOR»
		«ENDFOR»
	'''
)

This translates into invalid code, since the 'for' variable is not final, and so won't be usable in the anonymous function passed into 'map'.

The workaround:

class LoopVarFinal {
			
	def problem_1() ''' 
		«FOR i:1..10»
		«val final_i = i»
			«FOR j:(1..10).map(k | k*final_i) SEPARATOR " ... "»«j»«ENDFOR»
		«ENDFOR»
	'''

----

Sure enough, the generated code for "for" omits the final qualifier for the loop variable.

Same problem exists in 'straight' Xbase (still in Xpand):
 
	def problem_2() {
		for (i : 1..10) {
			for (j : (1..10).map(k | k*i)) {
				print(" " + j + " ");
			}
		}
	}

But! The problem is really bigger than that: 

var lim = 37;
val numbers = (1..100).filter(i | i <= lim);

So, formals and vals are final, but vars and for-loop variables are not.
IMHO, the user should not have to care: Non-final free variables in anonymous functions should be frozen as finals at the place of function initialization -- OR -- the problem should be detected and checked (if fixed for 'for-loops' the problem should be limited to 'var').

Applicable versions:
org.eclipse.xtext.xbase (2.0.0.v201106010845) "Xbase Model" [Active]
org.eclipse.xtext.xbase.doc (2.0.0.v201106010845) "Xbase Language's User Guide" [Resolved]
org.eclipse.xtext.xbase.junit (2.0.0.v201106010845) "Xbase Junit support" [Resolved]
org.eclipse.xtext.xbase.lib (2.0.0.v201106010845) "Xbase Runtime Library" [Resolved]
org.eclipse.xtext.xbase.ui (2.0.0.v201106010845) "Xbase UI" [Active]
org.eclipse.xtext.xtend2 (2.0.0.v201106010845) "Xtend2 Model" [Active]
org.eclipse.xtext.xtend2.doc (2.0.0.v201106010845) "Xtend2 Language's User Guide" [Resolved]
org.eclipse.xtext.xtend2.lib (2.0.0.v201106010845) "Xtend2 Runtime Library" [Resolved]
org.eclipse.xtext.xtend2.ui (2.0.0.v201106010845) "Xtend2 UI" [Active]

FWIW: Xtext rocks, thanks guys!