Frank Benoit wrote:
> Daniel Keep schrieb:
>> Ok.  What do you propose to do with this TypeInfo?
>>
>> The ONLY thing a given TypeInfo_Class gives you is the ClassInfo, which you already have.  The TypeInfo object itself gives you getHash, equals and compare, all of which are in Object and thus redundant, tsize which is the size of a pointer, swap which I can't see a use for, next which is useless, init which is also redundant and flags which is already in ClassInfo.
>>
>> Again, why do you even want that specific TypeInfo when it is less useful than the ClassInfo?
>>
>>   -- Daniel
> 
> I need to have a "something" to retrieve and pass around to hold all
> available information about a type. Including classes, interfaces and
> primitives.
> Because of ClassInfo cannot have information about primitives, I need to
> work with TypeInfo.
> Because of I have that need to retrieve that "something" from any object
> reference also, i need a way from classinfo to typeinfo.
> 

I remember having to do something similar once.  I think I solved it by carrying around these:

> struct ExTypeInfo
> {
>     TypeInfo ti;
>     ClassInfo ci;
> }

That, or you could store them as Objects, and then use upcasts to work out which it is.

> if( auto ti = cast(TypeInfo) info )
>     // It's a general type info
>
> else if( auto ci = cast(ClassInfo) info )
>     // It's a class
>
> else
>     assert(false);

  -- Daniel

Daniel Keep schrieb:
> 
> Frank Benoit wrote:
>> Daniel Keep schrieb:
>>> Ok.  What do you propose to do with this TypeInfo?
>>>
>>> The ONLY thing a given TypeInfo_Class gives you is the ClassInfo, which you already have.  The TypeInfo object itself gives you getHash, equals and compare, all of which are in Object and thus redundant, tsize which is the size of a pointer, swap which I can't see a use for, next which is useless, init which is also redundant and flags which is already in ClassInfo.
>>>
>>> Again, why do you even want that specific TypeInfo when it is less useful than the ClassInfo?
>>>
>>>   -- Daniel
>> I need to have a "something" to retrieve and pass around to hold all
>> available information about a type. Including classes, interfaces and
>> primitives.
>> Because of ClassInfo cannot have information about primitives, I need to
>> work with TypeInfo.
>> Because of I have that need to retrieve that "something" from any object
>> reference also, i need a way from classinfo to typeinfo.
>>
> 
> I remember having to do something similar once.  I think I solved it by carrying around these:
> 
>> struct ExTypeInfo
>> {
>>     TypeInfo ti;
>>     ClassInfo ci;
>> }
> 
> That, or you could store them as Objects, and then use upcasts to work out which it is.
> 
>> if( auto ti = cast(TypeInfo) info )
>>     // It's a general type info
>>
>> else if( auto ci = cast(ClassInfo) info )
>>     // It's a class
>>
>> else
>>     assert(false);
> 
>   -- Daniel

Ick! Right, that is doable.
But still, D lacks this navigation and it should be added.
Working with Object is really the ugly way.

Frank Benoit schrieb:
> I need to retrieve an instance of TypeInfo from an object instance at runtime.
> 
> TypeInfo info = typeid(obj) // does not work, only compile time
> 
> TypeInfo info = obj.classinfo.????; // how to navigate to TypeInfo?
> 
> Is that possible?
> If not, why? And can it be added (D1)?

See also: http://d.puremagic.com/issues/show_bug.cgi?id=2836

Frank Benoit wrote:
> I need to retrieve an instance of TypeInfo from an object instance at
> runtime.
> 
> TypeInfo info = typeid(obj) // does not work, only compile time
> 
> TypeInfo info = obj.classinfo.????; // how to navigate to TypeInfo?
> 
> Is that possible?
> If not, why? And can it be added (D1)?

I also did hit this issue. Fortunately, I never get a ClassInfo of a class whose static type I didn't see at least once before. This means I can get both the TypeInfo and ClassInfo from the static type, and put them into a global AA like ClassInfo[TypeInfo].

On Wed, 15 Apr 2009 02:41:50 -0400, Frank Benoit <keinfarbton@googlemail.com> wrote:

> Daniel Keep schrieb:
>> Ok.  What do you propose to do with this TypeInfo?
>>
>> The ONLY thing a given TypeInfo_Class gives you is the ClassInfo, which
>> you already have.  The TypeInfo object itself gives you getHash, equals
>> and compare, all of which are in Object and thus redundant, tsize which
>> is the size of a pointer, swap which I can't see a use for, next which
>> is useless, init which is also redundant and flags which is already in
>> ClassInfo.
>>
>> Again, why do you even want that specific TypeInfo when it is less
>> useful than the ClassInfo?
>>
>>   -- Daniel
>
> I need to have a "something" to retrieve and pass around to hold all
> available information about a type. Including classes, interfaces and
> primitives.
> Because of ClassInfo cannot have information about primitives, I need to
> work with TypeInfo.
> Because of I have that need to retrieve that "something" from any object
> reference also, i need a way from classinfo to typeinfo.
>


Frank, Daniel is right, TypeInfo_Class simply adds a classinfo member.  Each class type does not use a different TypeInfo derivative, it simply uses a different *instance*.  For everything that doesn't use the classinfo member in TypeInfo_Class, you can use Object's typeinfo, which should be accurate.

For everything else, use the classinfo.

Functions that you can use from Object's typeinfo:

getHash
equals
compare
tsize
flags
swap
next
init


Functions that use classinfo:

offTi
toString
opCmp
opEquals

Which you can simply call classinfo's appropriate functions.

You can also easily build a TypeInfo_Class based on the object:

scope info = new TypeInfo_Class();
info.info = obj.classinfo;

-Steve

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

>
>
> davidl wrote:
>> 在 Wed, 15 Apr 2009 10:14:42 +0800，Jarrett Billingsley
>> <jarrett.billingsley@gmail.com> 写道:
>>
>>> 2009/4/14 davidl <davidl@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.

-- 
使用 Opera 革命性的电子邮件客户程序: http://www.opera.com/mail/

On 2009-04-16 12:18:31 +0200, davidl <davidl@nospam.org> said:

> 在 Wed, 15 Apr 2009 13:56:20 +0800，Daniel Keep  <daniel.keep.lists@gmail.com> 写道:
> 
>> 
>> 
>> davidl wrote:
>>> 在 Wed, 15 Apr 2009 10:14:42 +0800，Jarrett Billingsley
>>> <jarrett.billingsley@gmail.com> 写道:
>>> 
>>>> 2009/4/14 davidl <davidl@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.

For people interested in runtime introspection tango.core.RuntimeTraits might be interesting.

Fawzi

Fawzi Mohamed schrieb:

> For people interested in runtime introspection tango.core.RuntimeTraits might be interesting.
> 
> Fawzi
> 

After the next tango release :)