I know meanings, but never have seen before this construction: "it is not to have had to plan this dinner"
Here is entire sentence from book Main Street by Sinclair Lewis:
If you only knew how wonderful it is not to have had to plan this dinner, and order it at the butcher's and fuss and think about it, and then watch Bea cook it!
The construction looks complicated, but it is made of simple parts. It works something like this:
How wonderful it is is an inversion of it is wonderful.
It is wonderful (not) to...(verb phrase)
The action that we are talking about is plan this dinner.
If you are required to plan this dinner, you have to plan this dinner.
If you are describing the experience of being required to plan this dinner in the present perfect, you have had to plan this dinner.
Put all of that together, and you get It is wonderful not to / have had to plan this dinner, which is a fancy way of saying "I did not have to plan this dinner, and that fact is wonderful"!
