Project Elvis

[Satoshi]

On Sunday, 29 October 2017 at 20:37:21 UTC, bauss wrote:
> On Sunday, 29 October 2017 at 20:15:41 UTC, Ola Fosheim Grøstad 
> wrote:
>> [...]
>
> But casting to bool is what you use to tell whether something 
> is valid or not.
>
> true = valid, false = invalid.
>
> If you want 0 to be valid for a type then you wrap around it 
> with opCast.
>
> Ex.
>
> ---
> import std.stdio;
>
> struct MyInt
> {
> 	int value;
> 	
> 	bool opCast(T : bool)()
> 	{
> 		return value >= 0;
> 	}
> }
>
> void main()
> {
> 	MyInt a = MyInt(1);
> 	MyInt b = MyInt(0);
> 	MyInt c = MyInt(-1);
> 	
> 	if (a) writeln("a is valid");
> 	if (b) writeln("b is valid");
> 	if (c) writeln("c is valid");
> }
> ---
>
> Output:
> a is valid
> b is valid

TL;DR

This could be done by maybe monad.

int? a = 0;
if (a) writeln("a is valid");



BTW: Thanks for implementing the Elvis feature.