• Cherry (28/28) Aug 29 2016 Greetings All
• Cherry (6/6) Aug 29 2016 How about having traits like hasOuter and getOuter (analogous to
• Jacob Carlborg (5/8) Aug 30 2016 Use the ".outer" property [1].
• deed (20/21) Aug 30 2016 class InnerBase { int a = 1; }

Cherry <cherry blossom.com> writes:

Greetings All

Can you help me with this code? I could not find any traits or 
other way to get me outer object of a given inner object. As for 
the context, I am fiddling with D trying to write a (domain 
specific) generic baseclass library. InnerBase is part of the 
library I write and the end user would be coding Outer and Inner 
classes. I do not want to force him to write getOuter kind of 
function. I would prefer not to ask him to add a mixin as well.

Is that possible, or is forcing the user to add a mixin the only 
way out?

Regards
- Cherry

////////////////////////////////////////////////////

class InnerBase{}
class Outer {
   class Inner: InnerBase {}
}
void main() {
   Outer outer = new Outer;
   auto inner = outer.new Outer.Inner();
   foo(inner);
}
void foo(T)(T t) {
   // somehow access inner.outer -- inner -> this.outer
   // Can not change Inner class to introduce getOuter 
functionality
   // I have access to InnerBase though and can add code there
}

Cherry <cherry blossom.com> writes:

How about having traits like hasOuter and getOuter (analogous to 
hasMember and getMember)?

I can give it a shot to add these traits to D compiler. But would 
such a pull request be accepted? I mean of course the code in the 
pull-request has to meet review expectations, but would such a PR 
be accepted from required feature perspective?

Jacob Carlborg <doob me.com> writes:

On 2016-08-30 04:43, Cherry wrote:
 Greetings All

 Can you help me with this code? I could not find any traits or other way
 to get me outer object of a given inner object.

Use the ".outer" property [1].

[1] http://dlang.org/spec/class.html#nested

-- 
/Jacob Carlborg

deed <none none.none> writes:

On Tuesday, 30 August 2016 at 02:43:16 UTC, Cherry wrote:

 Can you help me with this code?

class InnerBase { int a = 1; }
class Outer {
     int b = 2;
     class Inner: InnerBase { int c = 3; }
}

void main() {
     Outer outer = new Outer;
     auto inner = outer.new Outer.Inner();
     foo(inner);
}

void foo (T) (T t) {
     import std.stdio : writeln;
     writeln(t.a);           // prints 1
     writeln(t.outer.b);     // prints 2
     writeln(t.c);           // prints 3
}

dmd v2.071.2-b2

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