enum abuse

[Dicebot]

On Friday, 28 February 2014 at 11:27:31 UTC, Mike wrote:
> I recently saw the following line of code:
>
> enum size = __traits(classInstanceSize, Foo);
>
> Why "enum"?  Is this the equivalent of "immutable auto" or 
> something?
>
> Mike

enum creates compile-time placement constant. It does not create 
any symbol in resulting binary. Value of such enum gets pasted 
straight into the context when used.

Most similar thing in C terms would have been `#define size 
__traits(classInstanceSize, Foo)`, alas from preprocessor issues 
not present in D :)

It is idiomatic D way to force compile-time evaluation of 
expression.