const again

[guslay]

I've always thought of enum a special case of constant value. Now I guess constants will become a special case of enum?

But seriously, I hope that in the end we will agree on the preferred way to define a constant value (of which we are not interested in taking the address of).

Currently there is const/invariant int, which take storage and in this specific case are so completely redundant that I never know which one to use. There is enum, which has all the requirement but feels odd to generalize (as suggested if enum was spelled "let" or "def" there would be no problem using it for both enumerations and constant values).

So whatever syntax is chosen, I hope it's the last!

gus

sambeau Wrote:

> Bill Baxter Wrote:
> 
> > Paul Anderson wrote:
> > > Walter Bright Wrote:
> > > 
> > >> That leaves what to do about manifest constants. It occurs that we 
> > >> already have a mechanism for them - enums. So why not:
> > >> 	enum x = 3;
> > >> 	enum long y = 4;
> > >> ? I think that solves our problem.
> > >>
> > >> There's one last problem:
> > >> 	class C { }
> > >> 	const(C)[] a;
> > >> 	a[3] = new C();  // error, x[3] is const
> > >> does not work with this new regime. Every twist we tried to make it work 
> > >> caused other problems. Eventually, it just became clear that this just 
> > >> is not going to work. But, the following does work:
> > >> 	a ~= new C();
> > >> 	a = a[1..3];
> > >> 	a = b;
> > >> just like for strings. One can copy, concatenate, and slice such arrays 
> > >> (just like for strings). It's not so bad. Andrei also mentioned the 
> > >> possibility of using a template:
> > >> 	TailConst!(C)[] a;
> > >> which would do whatever was necessary under the hood to allow the 
> > >> elements of a to be rebound while still keeping the contents of the C 
> > >> objects const.
> > > 
> > > I don't care for 'enum' used in this way. It distracts from (dilutes?) the meaning as an enumerated type.
> > > 
> > > How about final?
> > > 
> > > final x = 3;
> > > final real y = 7.5;
> > > 
> > > 'final' is already a keyword and it's already used to declare one flavor of const in Java.
> > > 
> > > Paul
> > > 
> > 
> > That's not bad either.  final, alias, macro -- they all make more sense 
> > than reusing 'enum' for manifest constants that aren't really 
> > enumerating anything.
> > 
> > --bb
> 
> how about replacing 'enum' with 'def'
> 
> def X { A, B, C }
> def { A, B = 5+7, C, D = 8, E }
> 
> def int A = 0;
> def int B = 1;
> def int C = 2;
> 
> def x = 3;
> def long y = 4;
> 
> Then we aren't changing the implementation, just the semantics so that they fit the implementation better. 
> 
> ... thoughts?
> 
>