Can I make a variable public and readonly (outside where was declared) at same time?

[Ali Çehreli via Digitalmars-d-learn]

On 09/26/2014 10:16 AM, AsmMan wrote:

 > I know I can combine it by making an extra variable plus a property like
 > this:

That's the proper way of doing it in D.

If it's too much work, it is possible to take advantage of mixins to 
reduce the boilerplate. I found the following code among my D samples; 
it must have been found on these forums.

Defining without "set" would disallow the setter:

     alias AutoImplementedProperty!(string, "get") title;

The code:

import std.stdio;

class Bar
{
     alias AutoImplementedProperty!(string, "get", "set") title;
}

template AutoImplementedProperty(T, args...)
{
     import std.typetuple;
     @property
     {
         private T _name;
         static if (args.length)
         {
             static if (staticIndexOf!("get", args) > -1)
             {
                 public T AutoImplementedProperty()
                 {
                     return _name;
                 }
             }

             static if (staticIndexOf!("set", args) > -1)
             {
                 public void AutoImplementedProperty(T value)
                 {
                     _name = value;
                 }
             }

         }
     }
}

void main(string[] args)
{
     Bar a = new Bar();
     a.title = "asf";
     writeln(a.title);

     return;
}

 > I wanted to do that without this a_ extra variable

If the value is set only once and it is known during construction, it is 
indeed mark the variable public const:

import std.stdio;

class Foo
{
     public const int a;

     this (int x)
     {
         a = 2 * x;
     }
}

void main()
{
     Foo f = new Foo(21);
     writeln(f.a); // output value of a

     Foo f2 = f;    // copy works
     f2 = f;        // assignment works

     // f.a = 10; // compile error: a is readonly outside Foo's methods.
}

Ali