Re: [boost] C++0x question

From: Andrey Semashev (andysem_at_[hidden])
Date: 2007-10-16 11:51:47

Andrew Sutton wrote:
>> I would like to ask you if someone has never dreamed of something like
>>
>> try well_formed
>> {
>>
>>   .... your code here...
>>
>> } catch {
>>
>>   .... fall back code in case former is not compilable...
>>
>> };
>>
>>
>> I would think this would be an extension that greatly will open new
>> gates to C++.
> 
> I think there are probably too many places where a compiler can fail.  
> Try to find all of the broken language aspects in Boost.Config, and  
> then generalize this solution to all of those. You'd end up having  
> this construct around, well, most of your program. The only viable  
> solution to this is the preprocessor - it's ugly, but it's been  
> effective for 30 years, and I don't see it going away any time soon :)

Preprocessor doesn't always save you. I had couple of times when I
needed to detect availability of a non-member type or function - mostly,
for portability reasons. This is where scary things like above or
__if_exists/__if_not_exists MSVC extension may come handy. I wonder if
concepts are able to do that.