Manifest constants (was const again)

[Bill Baxter]

Walter Bright wrote:
> Oskar Linde wrote:
>> Like others, I propose that manifest constants use the alias keyword. 
>> Alias is perfect for this.
> 
> alias does make sense up to a point, and that point is:
> 
>     alias int x = 3;
> 
> That makes no sense in the light of what alias currently does. 

Is there some reason why it matters what alias currently does?  I think 
this is why most people here are disagreeing with you about using 
"enum".  You seem to be looking from the language implementer's point of 
view and saying "which chunk of code do I have already implemented that 
would be easiest to change into something supporting manifest 
constants?".  Whereas most of us are looking at the *words* and saying 
"which of these words best describes what we're trying to do?"

Supporting  alias int x = 3  may be more difficult to implement than 
enum int x = 3  because it changes the role of alias.   But users of the 
language don't care.  It still makes perfect sense in terms of what 
'alias' *means*.  x becomes an alias for the literal '3'.  You can think 
of it as meaning

   alias x = cast(int)3;

but who wants to type that?  Since x will become something that acts a 
lot like an int variable, it makes sense to allow the use of the 
familiar "int x" declaration as well.


> Manifest 
> constants are not untyped, although their type can often be inferred 
> from their initializer, just like auto declarations.

So   alias x = 3  should work too, and probably be a polysemous constant 
when those exist.  I don't see a problem there.

--bb