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Document number: N3741

Date: 2013-08-30

Toward Opaque Typedefs for C++1Y, v2

by Walter Brown

Excerpt:

Although this paper is self-contained, it logically follows our discussion, begun several years ago in
N1706 and continued in N1891, of a feature oft-requested for C++: an opaque typedef, sometimes
termed a strong typedef. The earlier of those works was presented to WG21 on 2004-10-20 during
the Redmond meeting, and the later work was presented during the Berlin meeting on 2005-04-06.
Both presentations resulted in very strong encouragement to continue development of such a
language feature. Alas, the press of other obligations has until recently not permitted us to
resume our explorations.

Now with C++11 as a basis, we return to the topic. Where our earlier thinking and nomenclature
seem still valid, we will repeat and amplify our exposition; where we have new insights, we will
follow our revised thinking and present for EWG discussion a high-level proposal for a C++1Y
language feature to be known as an opaque alias. ...