[Ffmpeg-devel] [PATCH]Update Doxygen comments for libavutil/tree.h

Trent Piepho xyzzy
Tue Feb 27 04:16:59 CET 2007

On Mon, 26 Feb 2007, [iso-8859-1] M?ns Rullg?rd wrote:
> >>
> >> That would be the present simple tense.  It is the same form as "the
> >> car is driven".
> >
> > Or is "returned" in "NULL is returned." acting as a participial adjective?
> > For example, in "The car is damaged," the word damaged is not functioning
> > as a verb, but as an adjective.
> >
> > I guess if you say, "NULL is returned by the function," then clearly "is
> > retruned" is a verb in the present simple tense and the passive voice.
> I'm not sure it's possible to distinguish between those cases here.
> They are both valid, and they have the same meaning.

I found a page here, http://www.bartleby.com/64/C001/047.html, that has
some rules for telling if a participle is used as an adjective or as a
verb.  In this case, you're right that is a verb.  In something like,
"Where is the library book?  Is it lost?  Is it returned?" I think
'returned' would be an adjective.

> > Still, using the present simple after an if clause seems wrong to me.
> Why?
> BTW, you probably know formal English grammar better than I do, since
> I've hardly ever studied it properly.  I usually get it right, but I
> don't necessarily know why it's right.

It's been a long time.  It's my birthday today, and thinking about this all
this stuff I've forgotten is just making me feel older than I already do. :(

Anyway, normally the simple present is used for something which is
timeless.  Some sort of general truth you are stating.  Like, "If you heat
water, it boils." In that case, both "If you heat water" and "it boils" are
in the simple present.

In, "If an insertion happened, then NULL will be returned." The "If an
insertion happened" is in the simple past, which makes it a hypothetical
condition.  It just seems wrong to combine that with the simple present.
There's also the use of the passive voice, which I think changes things
too.  eg:  "If you heat water, it boils." (active) vs "If you heat water,
it is boiled (by you)." (passive)

The passive one seems wrong.  Something about how it now refers to the
action of you boiling the water as opposed to the making a statement about
the state of the water.

Anyway, I think this would be the correct way:

"If an insertion happens, then either key or NULL will be returned."

I think the use of the simple present instead of the simple past in the if
clause makes the statement less of a hypothetical statement about an unreal
situation, and more a statement about the result of possible future event.

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