Optional parameters?

[Cym13]

On Monday, 2 April 2018 at 09:31:35 UTC, Timoses wrote:
> On Sunday, 1 April 2018 at 15:54:16 UTC, Steven Schveighoffer 
> wrote:
>> I currently have a situation where I want to have a function 
>> that accepts a parameter optionally.
>>
>> I thought maybe Nullable!int might work:
>>
>> void foo(Nullable!int) {}
>>
>> void main()
>> {
>>    foo(1); // error
>>    int x;
>>    foo(x); // error
>> }
>
>
> Can somebody enlighten me what this topic is about?
>
> I thought an optional parameter would be as easy as
>
>     void foo(int i = 0) { writeln(i); }
>
>     void main()
>     {
>         int x;
>         foo(x);
>         foo(1);
>         foo();
>     }
>
> Is the Nullable!int approach because 'i' would always 
> "optionally" be 0 if not passed with above 'foo'?

Same feeling here, this situation really asks for a Null Object 
pattern, not nullable. It's sad that nullable isn't very good in 
that situation but trying to force it in place doesn't seem very 
reasonnable.