Hi! I shot myself again with elvis operator. Had ...

# language-evolution

[zokipirlo]

Hi! I shot myself again with elvis operator. Had similar bug months ago, but of course forgot it and was debugging it today again 🙃

private fun isGroupChatInfoExpired(groupChatInfo: GroupChatInfo): Boolean {
    return Epoch.currentEpoch > (groupChatInfo.epoch ?: 0 + GROUP_CHAT_INFO_VALID_TIME) //epoch is nullable
}

This is always true. To fix the problem`groupChatInfo.epoch ?: 0` must be in parenthesis like:

private fun isGroupChatInfoExpired(groupChatInfo: GroupChatInfo): Boolean {
    return Epoch.currentEpoch > ((groupChatInfo.epoch ?: 0) + GROUP_CHAT_INFO_VALID_TIME) //epoch is nullable
}

Is it possible to show some warning in IntelliJ (Android Studio) that this will possibly have a wrong evaluation?

[elizarov]

It might be possible to have an inspection that would add parenthesis on Alt+ENTER. However, it means that if I intended to write something ?: a + b, then I'll have to fix it to something ?: (a + b) which does not look very nice to my taste.

[zokipirlo]

It was logical for me that elvis operator have the highest priority, but I was totally wrong.
I'm not saying it's wrong how it is, just that it's dangerous to work without parenthesis, because it maybe doesn't work as it looks on the first sight.
God knows how many similar mistakes have all over the project, because it's hard to search for that now.

[Derek Peirce]

Perhaps there should be a general extension method orIfNull (or better named) so that this would be groupChatInfo.epoch.orIfNull(0), so that the () go just around the replacement value instead of also in front of groupChatInfo.

[elect]

a little hint for the future, if unsure, always put parenthesis and check alt+enter if Intellij suggests you to remove useless parenthesis, if you don't get that, then automatically their presence is vital