typeof()

[Steven Schveighoffer]

On Fri, 21 Oct 2011 08:07:57 -0400, Jacob Carlborg <doob at me.com> wrote:

> On 2011-10-21 13:07, Steven Schveighoffer wrote:
>> On Fri, 21 Oct 2011 03:20:09 -0400, Gor Gyolchanyan
>> <gor.f.gyolchanyan at gmail.com> wrote:
>>
>>> Actually, the best idea would be to enable full reflection (much more
>>> complete, then what we have now) by default and allow to remove it on
>>> demand.
>>> Just like the methods being virtual by default, but with ability to
>>> make them final.
>>
>> I disagree.
>>
>> 1. Virtual methods are more common than final ones. But in D, RTTI is
>> much less prevalent than CTTI.
>> 2. RTTI can be generated from CTTI, so if you want to *force* extended
>> RTTI on objects that don't declare their RTTI "filled out", it should be
>> possible.
>>
>>>
>>> On Fri, Oct 21, 2011 at 10:29 AM, Jacob Carlborg <doob at me.com> wrote:
>>>
>>>> I got the impression that you suggested that the current RTTI should  
>>>> be
>>>> removed and only be available if you're using the @rtti attribute.
>>
>> The current RTTI is pretty useless. The only true RTTI functions in
>> existence are the factory method (which is useless for classes without a
>> default ctor) and dynamic cast. Everything else in TypeInfo is easily
>> had with CTTI.
>
> It's useful, I use it in my serialization library Orange. I have my own  
> implementation that doesn't care about constructors. It's used for  
> deserialization, instead of the constructor a special method can be used.

Do you have access to the methods via RTTI?  I thought only the default  
ctor was accessible (and some other special methods such as opCmp, but  
those are hacks).

I admit I don't use RTTI enough to know what's available, you obviously  
have a better understanding of the state of things.

>
>> I think we need dynamic casting for sure, and the nature of how classes
>> are built requires it anyways. factory I'm not so sure we need to be
>> supported for every class. I'd rather get full RTTI info for hierarchies
>> that I'm going to use RTTI on (usually RTTI is used on a specific subset
>> of the types). Yes, it does not allow for certain types of tools or
>> scripting engines, but so what? If you want you can mark Object with
>> @rtti and get every class into RTTI.
>>
>> -Steve
>
> The problem is when you use third party types and they haven't used the  
> @rtti attribute.

This can still be done.  If you have the compile-time type you can always  
forcefully generate the run time info (I would expect such a feature when  
RTTI is fully developed).

If they don't specify the @rtti attribute, then perhaps the class isn't  
meant to be accessed via RTTI

My thoughts were, you'd specify @rtti on the base class of a hierarchy  
that you need to use RTTI on, and all derived classes would generate info.

In any case, I'm not looking to define the exact features, I'm just saying  
I think it could work as an opt-in attribute.

-Steve