bool concat patternmatching with switch

[monkyyy]

On Thursday, 30 May 2024 at 12:56:40 UTC, Salih Dincer wrote:
> On Tuesday, 28 May 2024 at 19:39:45 UTC, monkyyy wrote:
>> ```d
>> switch(i%3==0,i%5==0){
>>   case 1,1: return "fizzbuzz";
>>   case 0,1: return "buzz";
>>   case 1,0: return "fizz";
>>   case ?,?: return i.to!string;
>> }
>> ```
>
> Maybe smarter solutions can be produced with BitFlags. At least 
> it will be more readable...
>
> ```d
> import std.stdio;
> import std.typecons;
>
> enum Status
> {
>     Idle = 1 << 0,    // 0001
>     Running = 1 << 1, // 0010
>     Paused = 1 << 2,  // 0100
>     Stopped = 1 << 3  // 1000
> }
>
> void main()
> {
>     BitFlags!Status currentStatus;
>     currentStatus = Status.Running;
>     switch (currentStatus)
>     {
>         case Status.Idle:
>             writeln("Durum: Idle");
>             break;
>         case Status.Running:
>             writeln("Durum: Running");
>             break;
>         case Status.Paused:
>             writeln("Durum: Paused");
>             break;
>         case Status.Stopped:
>             writeln("Durum: Stopped");
>             break;
>         default:
>             writeln("Bilinmeyen durum");
>             break;
>     }
>
>     currentStatus = Status.Paused;
>
>     switch (currentStatus)
>     {
>         case Status.Idle:
>             writeln("Durum: Idle");
>             break;
>         case Status.Running:
>             writeln("Durum: Running");
>             break;
>         case Status.Paused:
>             writeln("Durum: Paused");
>             break;
>         case Status.Stopped:
>             writeln("Durum: Stopped");
>             break;
>         default:
>             writeln("Bilinmeyen durum");
>             break;
>     }
> }
> ```
>
> SDB at 79

your example doesn't show overlapping states and im confused why 
you set up bitshifting without using it

switching over an enum I believe is solved with a `with` block; 
going with the fizz buzz example, an `enum isfizz{true,false}` 
wouldnt provide clarity

do try to take your example as something that show overlaping 
states
```d

```d
nullable(T){
   T me; alias me this;
   bool isnull=false;
}
bool isvalid(USERNAME);//looks up a string in a database
bool authcheck(PASSWORD,USERNAME);//checks if user/pass match

switch(status,username.isnull,username.isvalid,password.isnull,password.authcheck(username){
   with(Status){
   case Running,0,1,0,1://ideal path
   case ?      ,0,1,0,1://reset server
   case Running,1,?,?,?://show guest account
   case ?      ,?,?,?,0://invalid password page
}}
```