Re: How to get child class Type and members from parent class?

[mipri via Digitalmars-d-learn]

On Wednesday, 20 November 2019 at 10:05:11 UTC, zoujiaqing wrote:
import std.stdio;

class A
{
    this(T)(T t)
    {

    }

    void write()
    {
        T _this = cast(T) this;
        writeln(this.v);

Here, class A knows that a 'v' member is present. So why not just
put that member in class A, and let B inherit it?  If this method
won't apply to some other child classes, you can have an
intermediate class that adds the v member and specializes this
method to use it, and all the v children can inherit from A 
through
that intermediary.

I think what you're wanting to do is a reversal of OO design.
Maybe you can use proper OO instead, or maybe you'd prefer a
discriminated union if different children will have different 
types
for v. Like in an FP lang: https://github.com/pbackus/sumtype

    }
}

class B : A
{
    string v = "hello";
}

void main()
{
    auto b = new B;

    writeln(b.write()); // print hello
}