I'd better have done it.

[birdeen's call]

I've just used it in a game and thought it might be incorrect. Is it?

 

[konungursvia]

No, but it is a bit awkward.

 

[2006]

I've just used it in a game and thought it might be incorrect. Is it?

I don't think it's awkward, although I don't know how it came up in your game.
Its meaning is clear and it can be quite appropriate to say.
It means that I should have done something, but I don't remeber if I did it or not. And if I (forgot to)(didn't) do it, there will be bad consequences to face.

A. Did you turn that water tap off before you left?
B. Oh shit! I don't remember. I'd better have done it. Otherwise there will be water all over the damn place when we get home.

 

[birdeen's call]

My sentence was, "I'd better not have got preoccupied." I knew I got preoccupied and I wanted to say, "It would be better if I hadn't got preoccupied." So, as there wasn't any problem with remembering anything, should I say, "I shouldn't have got preoccupied"?

 

[2006]

My sentence was, "I'd better not have got preoccupied." It's not suitable, from what you said below.
I knew I got preoccupied and I wanted to say, "It would be better if I hadn't got preoccupied." That is okay.
So, as there wasn't any problem with remembering anything, should I say, "I shouldn't have got preoccupied"? That is okay too.

2006

 

[BobK]

...
A. Did you turn that water tap off before you left?
B. Oh shit! I don't remember. I'd better have done it. Otherwise there will be water all over the damn place when we get home.

This is a persuasive example BC, but I think the 'better have + ppl' format is much more common in the 2nd person. As 2006 says, it means '... or else something bad will happen'. 'You have until Friday to do this essay, and you'd better have done it by then or else I won't be able to mark it in time.'


b