[GROOVY-3525] Null-safe dereference operator not available for subscript operator access to properties or array/list elements

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.6, 1.6.1, 1.6.2, 1.6.3, 2.4.0-beta-4
• Fix Version/s: 3.0.0-alpha-1
• Component/s: groovy-runtime
• Assignee: Daniel Sun
• Reporter: Marc Palmer
• Created: 14/May/09 08:00
• Updated: 11/Nov/20 02:00
• Resolved: 15/Oct/19 20:34

Description

The null-safe deref operator causes compiler errors if it is used with the subscript operator.

Take the following example:

def obj = [name:'Marc Palmer', occupation:'Whining user', ]

println obj?.name

This is fine. However if you want to use the subscript operator for property access:

def obj = [name:'Marc Palmer', occupation:'Whining user', ]
def propName = 'name'
println obj?[propName]

You get errors. Of course you can workaround this with:

def obj = [name:'Marc Palmer', occupation:'Whining user', ]
def propName = 'name'
println obj?.getAt[propName]
println obj?."$propName"

But this is quite ugly if you are in a situation where you need/want to use subscript, and also if this is done properly then we also get nullsafe deref of arrays, lists and sets, especially if they are nested:

def myList = null
println myList?[0]?['name']

Without this you have to write the equivalent of:

def myList = null
println myList?.getAt(0)?.getAt('name')

Can't Groovy do this for us?