[Issue 2836] Navigate from ClassInfo to TypeInfo
https://issues.dlang.org/show_bug.cgi?id=2836 Andrei Alexandrescu and...@erdani.com changed: What|Removed |Added Version|2.026 |D2 --
[Issue 2836] Navigate from ClassInfo to TypeInfo
http://d.puremagic.com/issues/show_bug.cgi?id=2836 Walter Bright bugzi...@digitalmars.com changed: What|Removed |Added Status|NEW |RESOLVED Resolution||FIXED --- Comment #3 from Walter Bright bugzi...@digitalmars.com 2009-05-12 10:45:19 PDT --- Done with dmd 1.045 and 2.030. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
Re: Navigate from ClassInfo to TypeInfo
Fawzi Mohamed schrieb: For people interested in runtime introspection tango.core.RuntimeTraits might be interesting. Fawzi After the next tango release :)
Re: Navigate from ClassInfo to TypeInfo
davidl wrote:
?? Wed, 15 Apr 2009 10:14:42 +0800??Jarrett Billingsley
jarrett.billings...@gmail.com :
2009/4/14 davidl dav...@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
Re: Navigate from ClassInfo to TypeInfo
Daniel Keep schrieb:
davidl wrote:
在 Wed, 15 Apr 2009 10:14:42 +0800，Jarrett Billingsley
jarrett.billings...@gmail.com 写道:
2009/4/14 davidl dav...@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
Or it can request the classinfo of the passed object. Hey, and now the
typeinfo please :)
Re: Navigate from ClassInfo to TypeInfo
Frank Benoit wrote:
Daniel Keep schrieb:
davidl wrote:
在 Wed, 15 Apr 2009 10:14:42 +0800，Jarrett Billingsley
jarrett.billings...@gmail.com 写道:
2009/4/14 davidl dav...@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
Or it can request the classinfo of the passed object. Hey, and now the
typeinfo please :)
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
Re: Navigate from ClassInfo to TypeInfo
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.
Re: Navigate from ClassInfo to TypeInfo
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
Re: Navigate from ClassInfo to TypeInfo
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.
Re: Navigate from ClassInfo to TypeInfo
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
Re: Navigate from ClassInfo to TypeInfo
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].
Re: Navigate from ClassInfo to TypeInfo
On Wed, 15 Apr 2009 02:41:50 -0400, Frank Benoit keinfarb...@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
Navigate from ClassInfo to TypeInfo
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)?
Re: Navigate from ClassInfo to TypeInfo
2009/4/14 davidl dav...@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.
Re: Navigate from ClassInfo to TypeInfo
在 Wed, 15 Apr 2009 10:14:42 +0800，Jarrett Billingsley jarrett.billings...@gmail.com 写道: 2009/4/14 davidl dav...@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 -- 使用 Opera 革命性的电子邮件客户程序: http://www.opera.com/mail/
