Re: Create custom data types

[Ali Çehreli via Digitalmars-d-learn]

On 04/29/2015 12:53 PM, Dennis Ritchie wrote:

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?

Once a piece of code works for a particular type or value, it is easy to 
convert it to a template by moving the type and the value to the 
template parameter list and replace all occurrences of those with 
template parameters:

- int -> T

- -32_000 -> minValue

- 32_000 -> maxValue

Here it is:

import std.exception;

struct CustomInteger(T, T minValue, T maxValue)
{
    T value_;

    alias value this;

    @property T value() const
    {
        enforce((value_ >= minValue) &&
                (value_ <= maxValue));

        return value_;
    }

    @property void value(T v)
    {
        value_ = v;
    }
}

unittest
{
    alias Balance = CustomInteger!(int, -32_000, 32_000);

    auto b = Balance(42);
    assert(b == 42);

    b = 40_000;

    void foo(int) {}
    assertThrown(foo(b));
}

void main()
{}

Ali