Re: Is enum static?

[Ali Çehreli]

On 08/08/2013 02:53 PM, Borislav Kosharov wrote:

> On Thursday, 8 August 2013 at 21:49:31 UTC, Ali Çehreli wrote:
>> On 08/08/2013 02:45 PM, Borislav Kosharov wrote:
>>> If I have any enum in a class is it one for all instances or one per
>>> instance? Also are enums one per thread or only one?
>>
>> More than that. :) enums are manifest constants.
>>
>> Imagine that enum as being pasted into source code as is. This used to
>> have surprising effects for AAs, as an enum AA would be instantiated
>> from scratch everywhere that AA enum was used in the code. Perhaps it
>> is still that way...
>>
>> Ali
>
> What do you mean by AA? So enums are compile time constants that are
> like mini C macros?
Yes. For example:

enum fileName = "abc.txt";

Here is the problem with AA manifest constants:

import std.stdio;

enum string[int] aa = [ 1 : "one", 10 : "ten" ];

void main()
{
    writeln(1 in aa);
    writeln(1 in aa);
}

That program outputs different element addresses for the two 'in' 
operators because unfortunately the code is the equivalent of the following:

    writeln(1 in [ 1 : "one", 10 : "ten" ]);
    writeln(1 in [ 1 : "one", 10 : "ten" ]);

Ali