Re: [boost] Re: [network] An RFC posted to the sandbox

From: Jeff Garland (jeff_at_[hidden])
Date: 2005-04-16 17:10:24

On Sat, 16 Apr 2005 22:11:07 +0100, Andy Little wrote
> "Bob Bell" <belvis_at_[hidden]> wrote
> 
> > I'd rather approach it the other way around. Instead of saying,
> > "Let's provide various constructors in case someone wants them",
> > we should say "Let's provide a constructor if we know there is a
> > demonstrated, reasonable need for it." Is there a reasonable need for
> > mutliple constructors which allow a user to specify time values in
> > multiple ways?
> > 
> > As for ambiguity, there's ambiguity to the compiler, which can
> > probably be worked around, and then there's ambiguity to a human,
> > which can be much more difficult to deal with. In another post, I
> > wrote as an example:
> > 
> >   timeout  t(100);
> > 
> > Is this 100 seconds? 100 milliseconds? 100 microseconds? With a
> > single constructor using a type like double with a very simple
> > meaning (i.e., seconds), there is no reader ambiguity, and the
> > interface becomes very simple. At the same time, implementing it
> > (converting to the underlying platform representation) is trivial.
> > If it were me, I'd think long and hard about whether any other
> > constructors are really necessary.
> 
> Sounds like you need a UDT for time.
> 
> See  http://www.servocomm.freeserve.co.uk/Cpp/physical_quantity/index.html
> 
> time::ys to time::yr   ( 1 yoctosecond = 1e-24 s)
> 
> OTOH I believe the boost date_time lib also has various udts for time

Yep.  The generalized type is time_duration, but there a bunch of unit types
so you can say things like:

time_duration td = seconds(10) + milliseconds(20) - nanoseconds(100);

So you can write your signature as:

void f(boost::posix_time::time_duration td);

and your clients can use all the other types to make their code clear.

Jeff