non-integral enums?

[Wang Zhen]

Thomas Kuehne wrote:
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> Is there any reason why enum-base-types are restricted to integers?
> 
> How about lifting the integer restriction and updating the documentaion:
> 
> http://digitalmars.com/d/enum.html (DMD-0.147)
> 
>> If an Expression is supplied for an enum member, the value of the
>> member is set to the result of the Expression. The Expression must be
>> resolvable at compile time. Subsequent enum members with no
>> Expression are set to the value of the previous member plus one
> 
> 
> new version:
> 
>> If an Expression is supplied for an enum member, the value of the
>> member is set to the result of the Expression. The Expression must be
>> resolvable at compile time. If EnumBaseType is a numerical type, 
>> subsequent enum members with no Expression are set to the value of
>> the previous member plus one.
> 
> 
> 
> http://digitalmars.com/d/enum.html (DMD-0.147)
> 
>> Named enum members can be implicitly cast to integral types, but
>> integral types cannot be implicitly cast to an enum type.
> 
> 
> new version:
> 
>> Named enum members can be implicitly cast to their EnumBaseType, but
>> the EnumBaseType cannot be implicitly cast to an enum type.
> 
> 
> Consequences:
> 
> 1) no changes for existing code
> 
> 2) enables float enums
> 
> # enum SpeedLimit : double
> # {
> #	SLOW = 6.1,
> #	FAST = 9.3
> # }
> 
> 3) enables struct enums
> 
> # struct S
> # {
> # 	int i;
> # 	float f;
> # }
> #
> # enum E : S
> # {
> # 	A = { i:1, f:2.2},
> # 	B = { i:1, f:3.2},
> # 	C = { i:0, f:3.2}
> # }
> 
> Thomas
> 
> 
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How different is enum from constants then?