C++ bounded::integer library

[david stone via Digitalmars-d]

On Saturday, 17 May 2014 at 17:31:18 UTC, bearophile wrote:
> I am reading all the slides in this page (some are still 
> missing and will be added later):
> https://github.com/boostcon/cppnow_presentations_2014
>
> Here are the slides of a nice talk, "Removing undefined 
> behavior from integer operations: the bounded::integer library":
>
> https://github.com/boostcon/cppnow_presentations_2014/blob/master/files/bounded_integer.pdf?raw=true
>
> Some design decisions are not good (like not throwing at 
> run-time on default, the long name, and more). Near the end of 
> the slides pack it shows that a bit of language support can 
> help improve both the syntax and the usage.
>
> Bye,
> bearophile

Hello bearophile. I am the presenter / author of said library, so 
I feel I should comment on this.

First, the default overflow policy. This is an issue I have 
struggled with a bit. The current default is to mirror built-in 
integers in terms of performance. If a user types 
bounded::integer<0, 10>, they get a type with no run-time checks. 
I did consider making bounded::throw_policy the default (right 
now, the typedef for that is bounded::checked_integer<0, 10>). My 
reasoning for this that I suspect this is the behavior that most 
people want. I could be convinced otherwise primarily by way of 
proving that compilers can optimize away the run-time bounds 
check for common cases: situations like the integer increment for 
a loop index variable. I've also considered a debug assert 
statement for the default.

Second, the name. If you have suggestions for something better, I 
am listening. I definitely understand the importance of common 
types being short. The previous version of this library had the 
namespace as bounded_integer and the class type as 
bounded_integer, so instead of bounded::integer<0, 10>, you had 
to refer to it as bounded_integer::bounded_integer<0, 10>, which 
was even worse. My ideal would probably be something like int<0, 
10>, but I'm not getting that for fairly obvious reasons. I do 
find myself not typing out the name of the type very often, 
though, preferring to let auto deduce the types for me.

You say you have more criticisms of the library design, so I hope 
they are nothing too fundamentally flawed. I would like to hear 
them so that I can fix them (or perhaps I addressed the issue in 
my talk? The video is not yet posted).

Thank you for the link :)