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From: Thomas Witt (witt_at_[hidden])
Date: 2002-05-17 08:54:10

Hash: SHA1

On Friday 17 May 2002 14:59, Douglas Gregor wrote:
> Would it suffice to document that the default combiner is "last_value<R>"
> (instead of the terribly underspecified "implementation defined").

I think this is helpful but not sufficient.

> and make
> a notation in the tutorial? Making the notation directly in operator() just
> "feels wrong".

I think it should be documented in operator() that it is combiner dependent
whether calling an empty signal is allowed. Maybe adding a footnote
explaining the return value problem would help.

I am used to Qt signal/slot and posix signals. To one of the fundamental
features of the signals and slots pattern is that the signaller
does not care about the clients listening. The signaller just makes the
information available.

So it never came to my mind that calling empty signals might be a problem. I
now know that it is problem and that there is good reason to implement it
that way, so I am not criticising the design. I just think there are quite a
few people with a similar background that might have the same rough start
when it is not documented at a prominent place.

Just my 2c


- --
Dipl.-Ing. Thomas Witt
Institut fuer Verkehrswesen, Eisenbahnbau und -betrieb, Universitaet Hannover
voice: +49(0) 511 762 - 4273, fax: +49(0) 511 762-3001
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