Today's Italian grammar topic comes up a lot in our live lessons in Toronto and builds on last week's topic. The futuro anteriore (or future perfect in English), expresses a future action which is completed before another future action. In other words, it's a past future event - an event which will be over and done with before another future event occurs. Or to put it yet another way, it's a future event that's in the past from the perspective of a later future event. (So from the perspective of the present it's in the future but from the perspective of a later future event, it's in the past!)
The problem most English-speakers have with this tense is that in everyday English we don't use it! We either use the the present or the past. For example...
When you finish your peas I'll give you dessert. (present)
When you've finshed your peas I'll give you dessert. (past)
A more formal way to say this would be...
When you will have finished your peas, I'll give you dessert. (future perfect)
We'll leave as soon as he calls. (present)
We'll leave as soon as he's called. (past)
We'll leave as soon as he will have called. (future perfect)
All of these sentences describe a future action (giving dessert, leaving) occurring after an earlier future action has been completed (finishing peas, calling). The tense of choice for this in Italian is always the futuro anteriore.
So how is it formed? A lot like the passato prossimo, except you take the future (not present) of avere or essere plus the past participle (form ending in -ato, -uto or -ito) of the verb describing the action.
leggere (to read) - avrai letto (you will have read)
fare (to make or do) - avranno fatto (they will have done)
As with the passsato prossimo, the participle of essere verbs agrees with the subject in gender and number.
uscire (to go out) - Mario sarà uscito. (Mario will have gone out.) BUT - Luisa sarà uscita.
Another neat use of the futuro anteriore is conjecture about the past.
Gina sarà tornata dal suo viaggio. - Gina must have returned from her trip!
Saranno state le sei quando siamo tornati. - It must have been 6:00 when we returned.
Quando avrai fatto i compiti, capirai meglio quest'argomento!