Re: [boost] [config] Using SD-6 macros

On June 13, 2015 10:01:33 AM EDT, Edward Diener wrote:

On 6/13/2015 7:13 AM, Rob Stewart wrote:

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On June 12, 2015 10:26:49 PM EDT, Edward Diener wrote:

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On 6/12/2015 1:05 PM, Peter Dimov wrote:

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Edward Diener wrote:

It seems to me that there's no macro for SD-6 itself though. When __cpp_something is not defined, you don't know whether this is because 'something' is not implemented or because SD-6 is not implemented.

What difference could it possibly make ? You test if a macro is defined and if it is not you try something else. If it is you have your answer.

If the absence of an SD-6 macro implies a feature is not implemented, then the absence of SD-6 support indicates nothing is implemented when that's the mechanism used for discovery of features.

But who cares ? Each SD=6 feature test stands on its own. I could care less if a determination is made "somehow" that SD-6 as a whole is not implemented. It doesn't buy me anything.

You're missing the point. If you can't determine whether SD-6 is available, then you can't just check for the presence of an SD-6 macro to decide whether a feature is available. If the macro isn't present, but SD-6 is supported, then the feature isn't available. If SD-6 isn't supported, then you don't know the answer. Maybe you mean to try an SD-6 macro to see that a feature is implemented and, if that fails, try other methods before giving up and declaring the feature missing. I suppose that a positive answer from an SD-6 macro could be more reliable, but that doesn't account for buggy support that Boost can't use. ___ Rob (Sent from my portable computation engine)