Re: [boost] Boost Units library preview

From: Ben Strasser (strasser.ben_at_[hidden])
Date: 2006-08-29 17:23:25

Jeff Garland <jeff <at> crystalclearsoftware.com> writes:

> On the right track, but this scares me a bit.
> I'm not sure I want conversions 
> in the facet code.  I think I'd rather the 
> user do that explicitly.

Actually if a global implicit conversion has 
been explicity made avaiable by the user then
the facet code will use it.

What should happen if the user tries to
print a unit for which no pre- and postfix
facet is in the locale? Should it fail or
just print the raw number type without them.

For the moment (on my local disk) it's 
implemented as the later but I will likly 
change that.

 
> Input is much harder...because you only have 
> access to an input iterator.  You 
> can't backtrack.  So suppose you want to 
> handle input like this:
>    10 m
>    10 meters
>    10 microseconds
> 
> The first 2 are a valid length -- the last 
> isn't.  Anyway, it's sticky.
Why isn't the last valid? 

Anyway, do you have any tips on how to parse 
such things? All I can think of breaks 
in certain situations. 

Perhaps I should only provide textual represenations 
I/O and let user handle this with getline or somthing
similar. Not very elegant.