On 7/3/2011 7:05 AM, John Bytheway wrote:
On 01/07/11 03:08, Joel Falcou wrote:
According to the schedule, review for the Type Traits Introspection library by Edward Diener starts this friday and run till July 10th.
This is not a review, but some initial thoughts:
You mention early in the docs the risk of ODR violations from declaring the same metafunction more than once. It seems to me that this is very likely to occur when multiple libraries want to introspect the same names. For example, if two libraries both include
BOOST_TTI_HAS_TYPE(type)
then I will not be able to use both these libraries in my program; is that right?
Correct.
This seems a serious deficiency. I feel it would be better to generate these macro metafunctions in a namespace specific to the code that wants to use them, rather than putting them all in boost::tti. That would essentially eliminate the risk of cross-library ODR violations. What is your motivation for putting all the macro metafunctions in the same namespace?
You have made a very good point. My intention, evidently misguided, was to put the generated metafunctions in the boost::tti namespace to avoid polluting the global namespace. But I see now that I should not have added a namespace at all and the end-user could then use the macros in whatever namespace he wants in order to avoid ODR violations, and/or just use the complicated macro form to create a unique name for the metafunction. Actually, of course, that still could be done, but a full metafuncion name of 'anamespace::boost::tti::has_type_mytype' is more gruesome than 'anamespace::has_type_mytype'. Thanks for pointing this out.