On Feb 11, 2014, at 11:20 AM, Brandon Benvie wrote:

> On 2/11/2014 11:04 AM, Allen Wirfs-Brock wrote:
>> 
>> I can't find any explicit mention of this in the meeting notes [1] where we decided to make Symbol a primitive type with a wrapper class.  However, I made the appropriate changes to the spec. immediately after that meeting when the discussion was fresh in my mind and I still think that throwing on Symbol(sym) is the right thing to do:
>> 
>> For the other primitive/wrapper types the following conventions apply:
>>   new Wrapper(prim)   //always creates a new Wrapper instances wrapping the supplied primitive value
>>   Wrapper(prim)            //always returns a primitive value derived by coercing the argument to the appropriate primitive type. Returns prim if same type.
>> 
>> At [1] we made different decisions for symbols and Symbol wrappers :
>>  new Symbol(arg)     // always throws, we don't support explicit creation of Symbol wrapper objects
>>  Symbol(arg)              // always returns a new, not previously observed, primitive symbol value
> 
> One consideration is that it still is possible end up with a Symbol wrapper and with the current spec there's no way to unwrap it.

Symbol.prototype.valueOf returns the primitive value of a Symbol wrapper  (note, I just fixed it in rev 23 so it and toString also work for unwrapped symbol value)

Allen


> The argument for having a Symbol wrapper at all was to enabled prototypal inheritance, so, in theory, we want to enable people to add methods to Symbol.prototype. When non-strict methods on Symbol.prototype are called, they'll encounter a wrapped Symbol object that they can't do much with since they can never get at the underlying Symbol primitive.
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On Feb 11, 2014, at 11:20 AM, Brandon Benvie wrote:

> One consideration is that it still is possible end up with a Symbol wrapper and with the current spec there's no way to unwrap it.

Symbol.prototype.valueOf returns the primitive value of a Symbol wrapper  (note, I just fixed it in rev 23 so it and toString also work for unwrapped symbol value)