Search⌘ K
Home
Courses
Advanced Programming Techniques in D

is (T == Specifier)

Explore how using is (T == Specifier) enables you to determine if a type exactly matches a given specifier in D. Understand how this facilitates conditional compilation and allows templates to adapt their behavior based on precise type checks.

We'll cover the following...

It is used to determine whether T is the same type as specifier or whether T matches that specifier.

Whether the same type or not?

Lets consider the example from the previous lesson and use == instead of :, the condition would not be satisfied for AlarmClock:

D
import std.stdio;



interface Clock {

    void tellTime();

}



class AlarmClock : Clock {

    override void tellTime() {

        writeln("10:00"); 

    }

}



void myFunction(T)(T parameter) {

    static if (is (T == Clock)) {

        // If we are here then T can be used as a Clock

        writeln("This is a Clock; we can tell the time"); 

        parameter.tellTime();

        

    } else {

        writeln("This is not a Clock"); 

    }

}

void main() {

    auto var = new AlarmClock; 

    myFunction(var); 

    myFunction(42);

}

Although AlarmClock ...