Re: Unexpected result of IsInstanceOf

[Ali Çehreli via Digitalmars-d-learn]

On 1/30/20 4:51 PM, Ben Jones wrote:
The following result doesn't make sense to me... how does isInstanceOf 
return false?


```
import std.traits;
import std.stdio;
import std.typecons;
auto f(T)(T t){
 return Nullable!T(t);
}
void main(){
     auto f3 = f(3);
     writeln(typeof(f3).stringof);
     writeln(isInstanceOf!(Nullable, f3));
}
```

outputs

```
Nullable!int
false
```


In this case it's an instance of a type template, which only types would 
be. So, you want to check whether typeof(f3) is an instance of Nullable.


Ali

Re: Unexpected result of IsInstanceOf

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

On Friday, 31 January 2020 at 00:51:45 UTC, Ben Jones wrote:

writeln(typeof(f3).stringof);
writeln(isInstanceOf!(Nullable, f3));


In the first one, you check typeof, but not in the second one.

writeln(isInstanceOf!(Nullable, typeof(f3))); // true

The template argument there was T above - the type, not the value.

Unexpected result of IsInstanceOf

[Ben Jones via Digitalmars-d-learn]

The following result doesn't make sense to me... how does 
isInstanceOf return false?


```
import std.traits;
import std.stdio;
import std.typecons;
auto f(T)(T t){
return Nullable!T(t);   
}
void main(){
auto f3 = f(3);
writeln(typeof(f3).stringof);
writeln(isInstanceOf!(Nullable, f3));
}
```

outputs

```
Nullable!int
false
```