For two days, I was trying to figure out what is wrong with our project after upgrading to Groovy 2.5. First of all, I’ve found that…
Why you should avoid using push and pop method on lists in Groovy
For two days, I was trying to figure out what is wrong with our project after upgrading to Groovy 2.5. First of all, I’ve found that java.util.Date extension methods are no longer part of groovy-all but this was quite easy as this is mentioned in the release notes.
[The Apache Groovy programming language - Groovy 2.5 release notes
groovy-lang.org
The other issue was much more cryptic to discover. After numerous hours I’ve found out that last item of the list in some method is not being removed. When I dig deeper I found a short note for apop method:
In other words, the following piece of code is no longer true after upgrading to Groovy 2.5. By the way, using << instead of push is a quite common habit.
List
numbers << ‘four’
// do something
String usedToBeLast = numbers.pop()
// passes until 2.5 upgrade
assert numbers == [‘one’, ‘two’, ‘three’]
I would say using pop is quite common as there was no simple shortcut to remove the last element of the list. On the other hand, push,add and << were used interchangeably as they were doing the same thing.
The only valid use case is to use push and pop in a symmetrical way:
List
numbers.push ‘four’
// do something
String usedToBeLast = numbers.pop()
// always passes
assert numbers == [‘one’, ‘two’, ‘three’]