Re: Using enum types

[Meta via Digitalmars-d-learn]

On Monday, 4 December 2017 at 22:34:41 UTC, helxi wrote:

Why can't enums be used as types in this (simplified) example?

enum Positivity
{
Positive,
Negative
}

struct Wave
{
public:
Positivity slope;
}

enum Waves
{
Sin = Wave(Positivity.Positive),
Cos = Wave(Positivity.Negative)
}

int nth_value(T : Waves)(int n);

int nth_value(T : Waves.Sin)(int n)
{
return n % 2 ? 1 : -1;
}

int nth_value(T : Waves.Cos)(int n)
{
return n % 2 ? -1 : 1;
}


We Adam said, Waves.Sin and Waves.Cos are values, while Waves 
itself is the type. You want to do the following:


int nth_value(Waves w: Waves.Sin)(int n)
{
//Etc.
}

At least I *think* that's what you want. I'm on mobile and dpaste 
is down so I have no way to double check the syntax, which I can 
never remember.

Re: Using enum types

[Adam D. Ruppe via Digitalmars-d-learn]

On Monday, 4 December 2017 at 22:34:41 UTC, helxi wrote:

enum Waves
{
Sin = Wave(Positivity.Positive),
Cos = Wave(Positivity.Negative)
}
writeln(nth_value!(Waves.Sin)(1));
}


Sin and Cos there are actually values, not types...

Using enum types

[helxi via Digitalmars-d-learn]

Why can't enums be used as types in this (simplified) example?

enum Positivity
{
Positive,
Negative
}

struct Wave
{
public:
Positivity slope;
}

enum Waves
{
Sin = Wave(Positivity.Positive),
Cos = Wave(Positivity.Negative)
}

int nth_value(T : Waves)(int n);

int nth_value(T : Waves.Sin)(int n)
{
return n % 2 ? 1 : -1;
}

int nth_value(T : Waves.Cos)(int n)
{
return n % 2 ? -1 : 1;
}

void main()
{
import std.stdio;

writeln(nth_value!(Waves.Sin)(1));
}