• Marcone (2/2) Nov 05 2020 How add class or struct member after construction? Is it possible
• H. S. Teoh (9/11) Nov 05 2020 You can't, because D is statically-typed.
• Simen =?UTF-8?B?S2rDpnLDpXM=?= (23/25) Nov 05 2020 This depends a lot on what you mean. The short answer is no - you
• Jacob Carlborg (17/19) Nov 08 2020 It depends on what needs you have. You can declare a free function that

Marcone <marcone email.com> writes:

How add class or struct member after construction? Is it possible 
in D? How?

"H. S. Teoh" <hsteoh quickfur.ath.cx> writes:

On Thu, Nov 05, 2020 at 10:48:38PM +0000, Marcone via Digitalmars-d-learn wrote:
 How add class or struct member after construction? Is it possible in
 D? How?

You can't, because D is statically-typed.

However, you *can* implement something equivalent manually by other
means, depending on your use case.  What use do you have in mind?  If
you're more specific about what you're trying to accomplish, we could
figure out a possible implementation for you.


T

-- 
Why waste time learning, when ignorance is instantaneous? -- Hobbes, from
Calvin & Hobbes

Simen =?UTF-8?B?S2rDpnLDpXM=?= <simen.kjaras gmail.com> writes:

On Thursday, 5 November 2020 at 22:48:38 UTC, Marcone wrote:
 How add class or struct member after construction? Is it 
 possible in D? How?

This depends a lot on what you mean. The short answer is no - you 
cannot. However, given some limitations, it is possible. What 
sort of members do you need to add, and how will you be using 
them?

For instance, this works:

struct S {
     import std.variant;
     Variant[string] members;

     Variant opDispatch(string name)() {
         return members[name];
     }
     Variant opDispatch(string name, T)(T value) {
         return members[name] = value;
     }
}

unittest {
     S s;
     s.foo = 13;
     assert(s.foo == 13);
}

--
   Simen

Jacob Carlborg <doob me.com> writes:

On 2020-11-05 23:48, Marcone wrote:
 How add class or struct member after construction? Is it possible in D? 
 How?

It depends on what needs you have. You can declare a free function that 
takes the class/struct as the first parameter and call it like a method [1]:

class Foo
{
     int a;
}

void printA(Foo foo)
{
     writeln(foo.a);
}

foo.printA();
printA(foo);

The two above lines are exactly the same.

[1] https://dlang.org/spec/function.html#pseudo-member

-- 
/Jacob Carlborg