Create custom data types

[Dennis Ritchie via Digitalmars-d-learn]

On Wednesday, 29 April 2015 at 17:52:27 UTC, Ali Çehreli wrote:
> On 04/29/2015 10:17 AM, Dennis Ritchie wrote:
>> Hi,
>> Is it possible to create simple D user-defined data types 
>> without the
>> use of classes and other OOP?
>>
>> For example, in Ada is done as follows:
>>
>> -----
>> type balance is new Integer range -32_000 .. 32_000;
>
> Something similar to the following solution should be in Phobos:
>
> import std.exception;
>
> struct Balance
> {
>     int value_;
>
>     alias value this;
>
>     @property int value() const
>     {
>         enforce((value_ >= -32_000) &&
>                 (value_ <=  32_000));
>
>         return value_;
>     }
>
>     @property void value(int v)
>     {
>         value_ = v;
>     }
> }
>
> unittest
> {
>     auto b = Balance(42);
>     assert(b == 42);
>
>     b = 40_000;
>
>     void foo(int) {}
>     assertThrown(foo(b));
> }
>
> void main()
> {}

Thanks.

On Wednesday, 29 April 2015 at 17:52:27 UTC, Ali Çehreli wrote:
> It should be easy to make a template of it. (I really think it 
> should already be in Phobos. :) )

Where can I find documentation on this subject?