DIP42

Title:	Add enum E(T) = expression; eponymous template support
DIP:	42
Version:	1
Status:	Implemented
Load:	Design Details
Created:	2013-06-24
Last Modified:	2013-06-24
Language:	D2
Breaks:	Nothing (extension)
Links:	DMD Pull request

Abstract

This pattern has become quite common in D:

   template isIntegral(T) {
     enum isIntegral = is(T : long) || is(T : ulong) || ...;
   }

Analogously to struct S(T), the enum manifest constant could be written as:

   enum isIntegral(T) = is(T : long) || is(T : ulong) || ...;

This is a natural fit for D. It does not break any existing code, and is simple to implement - it's just a rewrite in the parser.

The pattern is common, and a bit awkward. It's worth supporting the new syntactic sugar.

This document has been placed in the Public Domain.