[v3] ext/type_traits.h

Benjamin Kosnik bkoz@redhat.com
Thu Sep 28 14:14:00 GMT 2006

> In the use cases I've personally been involved with, I had an  
> integral type T which could be either signed or unsigned, and I  
> needed to get its unsigned counterpart (or signed counterpart).   
> Actually the former (unsigned counterpart) was my more common need.   
> Having to spell that typename __add_unsigned<typename  
> __remove_signed<T>::type>::type seems cumbersome.

All this seems unduly complicated to me.

TR1 already has traits for is_signed or is_unsigned. Together with
__conditional_type (hopefully spelled conditional_type in TR2 or wherever) gives:

// To get unsigned type.
conditional_type(is_signed<T>::value, add_unsigned<T>::type, T)

This seems reasonable to me, and quite readable.


C++ doesn't currently have "to" traits or utils. Why add them? If you
add this, will "to_const" be next?



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