Re: [boost] arithmetic meta functions and traits

Subject: Re: [boost] arithmetic meta functions and traits
From: Zachary Turner (divisortheory_at_[hidden])
Date: 2009-12-06 03:46:02

On Sun, Dec 6, 2009 at 2:28 AM, joel falcou <joel.falcou_at_[hidden]> wrote:

> Zachary Turner wrote:
>
>> Is there any use for something like this?  Following compiles on MSVC 9.0.
>> Despite the simplicity of the final template, it was *NOT* easy to get
>> this
>> working given that there's about 10 ways you should be able to do this
>> according to the standard, but poor SFINAE support makes it next to
>> impossible to get your compiler to accept anything.  Since it doesn't do
>> anything highly fancy, I would wager it works on GCC and other compilers
>> as
>> well, although it needs to be tested.
>>
>>
> I think there is already something like this proposed as an extension to
> type_traits and use sizeof tricks to do that.
>

The sizeof trick I'm aware of is comparing the size against an "unlikely"
size N, something very large such as 43280 such that you're unlikely to come
across two types P and Q such that sizeof(P()+Q()) == N.  Is there any
reason this method is preferable to the method I used above though, where it
can provably never result in a false negative?

Zach