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Document number: N4025

Date: 2014-05-23

Exploring classes of runtime size

by Jeff Snyder and Richard Smith

Excerpt:

During the Chicago meeting, several options were discussed for Arrays of Runtime Bound. These alternatives were summarised by Bjarne Stroustrup in N3810 [1]. One of the alternatives discussed, dubbed Array Constructors, was to introduce a core language feature that would allow types such as dynarray and bs_array to be written without special compiler support.

At the Issaquah meeting, J. Daniel Garcia proposed such a language feature, called Run-time bound array data members, in N3875 [2]. There was much discussion of this proposal, and of runtime-size types in general, with an overall feeling that it was worth pursuing a core language feature in this area.

This paper proposes an alternative way of allowing classes with runtime-bound array data members (aka runtime-size types) in C++ that aims to avoid various issues that were discussed at the Issaquah meeting, as well as exploring the impact that adding runtime-size types would have on the rest of the C++ language.