Manifest constants (was const again)

[Robert DaSilva]

Bruce Adams wrote:
> On Sat, 08 Dec 2007 19:44:50 -0000, Janice Caron
> <caron800 at googlemail.com> wrote:
> 
>> On 12/8/07, Walter Bright <newshound1 at digitalmars.com> wrote:
>>> No, that would be:
>>>
>>>      enum defname = "upload.log";
>>>      enum float fudge = 61.74;
>>>      enum char starter = 'r';
>>>      enum qwerty = 0xF4;
>>>      enum foobar = SomeFunc("foobar");
>>
>> The first one is interesting. Can I do
>>
>>     enum s = "hello";
>>     auto p = s.ptr;
>>
>> ?
> 
> You're just evil aren't you? If its a manifest constant you can't take
> its address
> without making it manifest beyond the compiler. That means the .ptr
> property is not useable.
> I think that should be a compile time error.
> 
> I don't really understand the problem myself.
> I always thought it was common sense that a 'simple' constant should
> only take
> up space:
> 
> 1) If it is used
> 1a) if it is never used it should use no space
> 1b) if it is used only a few times its the compilers decision whether to
> place it in .bss
> 2) If you need to take the address of it
> 
> I had assumed this was the case in D.
> I guess the problem is to do with modules. You don't know at compile
> time whether it will
> be used. So I guess you do need a way to say don't use any space after all.

It would be valid because "hello".ptr is valid, but &1 isn't valid. See
the difference?