When I am saying:
Upon request, the homework has to be handed in to the teacher.
does this imply, that it is the teacher who is requesting? Or could it also be, say, the director?
If in the above sentence it is not necessarily the teacher, could I then express this by saying:
The homework has to be handed in to the teacher upon his/her request.
This clearly states that the teacher requests, but is this something which is said? (It sounds a bit awkward to me.)
As Macmillan
on request ... used for saying that something will be done if someone asks for it
shows, the agent issuing the request is not specified.
Note that Farlex gives the temporal reading:
on request – on the occasion of a request.
But pragmatically, the most obvious candidate (the teacher here) would be assumed and should be intended.
..........
'At his request' sounds more natural than 'on his request', but suggests 'if he asks for it' rather more than 'when he asks for it'.
See Chaz's answer at forum.wordreference, where the temporal sense that may well be better indicated by 'on his request' is mentioned. The phrase is also said to sound a little unusual in the Wordreference Forum thread, though not unacceptable.
Definition of by/on/upon request (M-W)
: by asking for something usually in a formal way
Catalogs are available by/on/upon request.
"Upon request, the homework has to be handed in to the teacher" means "When asked for, the homework has to be handed in to the teacher". Who asks? Of course, it is teacher, as per the context. It seems there is nothing awkward in it.
