[GROOVY-890] Allow sublists as lvalue in range notation

• Type: Wish
• Status: Closed
• Priority: Trivial
• Resolution: Fixed
• Affects Version/s: 1.0-JSR-1
• Fix Version/s: 1.1-beta-2
• Environment: Groovy Version: 1.0-jsr-01 JVM: Blackdown-1.4.2-01
• Assignee: Paul King
• Reporter: Jochen Hinrichsen
• Created: 15/Jun/05 12:27
• Updated: 26/Sep/07 20:32
• Resolved: 11/Jun/07 04:08

Description

In my opinion it would be nice to allow for lvalue slicing using the range operator. Example: reverse the first n elements of a list

// throws IllegalArgumentException
list[0..<n] = list[0..<n].reverse()

The exception is thrown in DefaultGroovyMethods.java ("You must specify a list of 2 indexes to create a sub-list") for all n != 2 (i.e. almost always)

Rewriting the statement as

list[0, n-1] = list[0..<n].reverse()

works but is not as nice.

It might be enough to change DefaultGroovyMethods.java from

if (splice.size() != 2)

{ throw new IllegalArgumentException("You must specify a list of 2 indexes to create a sub-list"); }

int left = InvokerHelper.asInt(splice.get(0));
int right = InvokerHelper.asInt(splice.get(1));

to

int left = InvokerHelper.asInt(splice.get(0));
int right = InvokerHelper.asInt(splice.get(splice.length()));

but i'm not sure what other parts are affected 'cause i'm a complete newbie

Thanks

Jochen