[boost] Re: win32.hpp and min/max macros

From: Eric Niebler (eric_at_[hidden])
Date: 2004-02-24 12:14:35

David Abrahams wrote:

> They all compile and run the following:
> 
>   namespace std {
>     template<class T> const T& min(const T& a, const T& b) { return a<b?a:b; }
>   }
>   int main()
>   {
>       int x = 0;
>       int y = 1;
>       return (std::min)(x,y);
>   }
> 
> But where will the definition of min come from on broken stdlib
> implementations?
> 

Changing a call from min(a,b) to (min)(a,b) would break on stdlib 
implementations that *only* have the min/max macros and not the min/max 
algorithms, is that what you're saying? Do such implementations exist? 
We'll have to provide the min/max algorithms for such platforms, I 
suppose. Which platforms are affected?

> 
>>   Also, I'm not a CVS guru. If all
>>   hell breaks loose as a result of this change, is there someone
>>   willing to help me back it out?
> 
> 
> Just "cvs tag" to mark the state before you start making changes and
> it'll be comparitively easy.
>

Guess I should have done that before the 800 edits, huh? Hmm ...

>>
>>4) This is the sort of thing developers will forget to do even if it's
>>   in a style guide. A simple way of ensuring this stays fixed would
>>   be to run the regressions with min() and max() #defined to garbage,
>>   so that violations are detected and corrected early. Is this
>>   possible?
> 
> 
> Yes, it's possible, but that'll only detect the usage:
> 
>      min(x,y)
> 
> and not
> 
>     std::min(x,y)
> 
> both of which are going to be banned, right?
> 

Why would it not detect the second? If I #define min(a,b) to garbage, 
then the above becomes:

     std::garbage;

Mission accomplished.

-- 
Eric Niebler
Boost Consulting
www.boost-consulting.com