Navigate from ClassInfo to TypeInfo

[davidl]

在 Wed, 15 Apr 2009 13:56:20 +0800，Daniel Keep  
<daniel.keep.lists at gmail.com> 写道:

>
>
> davidl wrote:
>> 在 Wed, 15 Apr 2009 10:14:42 +0800，Jarrett Billingsley
>> <jarrett.billingsley at gmail.com> 写道:
>>
>>> 2009/4/14 davidl <davidl at nospam.org>:
>>>>
>>>> Send this object to vararg func, and retrieve the TypeInfo there and
>>>> return?
>>>
>>> No.  The typeinfo passed to vararg functions is also determined at
>>> compile-time.
>>
>> so it's a bug?
>>
>> I think vararg funcs always want the real typeinfo of the object
>
> No, they get the typeinfo of what they're passed.
>
>> class A {}
>> class B : A {}
>>
>> void foo(...) {}
>>
>> void bar(A a) { foo(a); }
>>
>> void main()
>> {
>>     scope b = new B;
>>     bar(b);
>> }
>
> bar cannot possibly know what the "real" TypeInfo of a is.  But that
> doesn't matter because it's passing an A with A's TypeInfo.  And if foo
> is maybe interested in Bs, then it can just try to up-cast.
>
>   -- Daniel

If the caller only sends the object typeinfo, then the vararg typeinfo is  
so limited to be valid for primitives. It's definitely useless for classes  
cases.

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