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December 16, 2010
List of derived types?
Greetings

I need a way to know (using traits or other compile time constructs)
all the types derived from a given type.
Is it possible in D?

Is it possible to get a list of all the user-defined classes? I could
use that to filter out the classes that I need.

Regards
Cherry
December 16, 2010
Re: List of derived types?
V Thu, 16 Dec 2010 18:46:41 +0530, d coder wrote:

> Greetings
> 
> I need a way to know (using traits or other compile time constructs) all
> the types derived from a given type. Is it possible in D?
> 
> Is it possible to get a list of all the user-defined classes? I could
> use that to filter out the classes that I need.
> 
> Regards
> Cherry

you can iterate all modules to find base classes. see object_.d file to 
see sturcture of TypeInfo_Class or ModuleInfo.

    foreach(m; ModuleInfo)
       foreach (c; m.localClasses)
           if (c.base !is null)
               writefln(c.base.name);
December 16, 2010
Re: List of derived types?
On 12/16/2010 02:16 PM, d coder wrote:
> Greetings
>
> I need a way to know (using traits or other compile time constructs)
> all the types derived from a given type.
> Is it possible in D?
>
> Is it possible to get a list of all the user-defined classes? I could
> use that to filter out the classes that I need.
>
> Regards
> Cherry

I'm curious, why do you need that?
December 16, 2010
Re: List of derived types?
d coder <dlang.coder@gmail.com> wrote:

> Greetings
>
> I need a way to know (using traits or other compile time constructs)
> all the types derived from a given type.
> Is it possible in D?

No.

> Is it possible to get a list of all the user-defined classes? I could
> use that to filter out the classes that I need.

No.


However, it is possible at run-time to iterate through all classes and
at that time compare them to the base class:

T[] getDerivedClasses( T )( ) if ( is( T == class ) ) {
    T[] result;
    foreach ( mod; ModuleInfo ) {
        foreach ( cls; mod.localClasses ) {
            if ( mod.name == "object" ) {
                break;
                }
            auto cls_base = cls;
            do {
                if ( cls_base.name == T.classinfo.name ) {
                    if ( T tmp = cast(T)cls.create( ) ) {
                        result ~= tmp;
                    }
                }
            } while ( ( cls_base = cls_base.base ) != Object.classinfo );
        }
    }
    return result;
}


-- 
Simen
December 16, 2010
Re: List of derived types?
> I'm curious, why do you need that?
>

It is a long story.

But basically I am creating a platform wherein the users would be
deriving classes from some base classes that I write as part of the
platform. And the users would often be deriving many such classes.

The end-users would often not be programmers and would know little D
(as you can see I am also learning D :-). I want to automate some code
generation for them and I hope to do that by creating wrapper classes
that would shadow the classes that the end-users have written. Since
the and users would be instantiating these classes only inside a
particular class scope, I wanted to create some code inside that class
scope. Right now I am forcing the end-users to insert some mixin for
every class that they code. I wanted to automate that process.

Hope what I said makes sense to you.

Regards
Cherry

Hope what I said makes sense.
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