Dart : Callable Classes

Ravi Kishor

29 December 2023

In this article, we are going to learn about the Callable classes in Dart.

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Introduction- Callable Classes

As the name “Callable” points out for calling something. Dart facilitates us to call the class instances like a function with the help of the Call() function.
Basically, If we want to call a class instance as a function then we need to implement the call() function in it.
The call () method supports the same functionality as normal functions such as parameters and return types.

Syntax

class your_class_name {
 
  
  return_type call ( parameters ) {
    ... // function code
  }
  
}

class your_class_name {

return_type call ( parameters ) {

... // function code

}

Implementation

class myCallableClassExample {


String call(String a, String b, String c) => ' $a $b $c !'; 
//  call method which to make create the class callable

}

void main() {
// Creating instance of class
var callableClassInstance = myCallableClassExample();
var callableClassReturn = callableClassInstance('Hello', 'Team', 'Mobikul');

print(callableClassReturn);
}

class myCallableClassExample {

String call(String a, String b, String c) => ' $a $b $c !';

// call method which to make create the class callable

}

void main() {

// Creating instance of class

var callableClassInstance = myCallableClassExample();

var callableClassReturn = callableClassInstance('Hello', 'Team', 'Mobikul');

print(callableClassReturn);

}

Result:

Callable function example for int return type

class myCallableClassExample {


int call (int a,int b, int c)=>a+b+c;//  call method  make create the class callable
  

}

void main() {

 var callableClassInstance = myCallableClassExample();// Creating instance of class
 var callableClassReturn = callableClassInstance(5, 10, 15);
  
   print(callableClassReturn);
}

class myCallableClassExample {

int call (int a,int b, int c)=>a+b+c;// call method make create the class callable

}

void main() {

var callableClassInstance = myCallableClassExample();// Creating instance of class

var callableClassReturn = callableClassInstance(5, 10, 15);

print(callableClassReturn);

}

Result:

Till now, we know about call function and how to implement them to make a class callable.
Now A question arises, Can we create multiple call functions for a class?

The answer is NO. Dart doesn’t allow us to create multiple call() functions for a class.

Let’s check it with an example.

class myCallableClassExample {


int call (int a,int b, int c)=>a+b+c;//  Fisrt call method  make create the class callable
  int call (int a,int b, int c)=>a+b+c;// Second call method

}

void main() {

 var callableClassInstance = myCallableClassExample();// Creating instance of class
 var callableClassReturn = callableClassInstance(5, 10, 15);
  
   print(callableClassReturn);
}

class myCallableClassExample {

int call (int a,int b, int c)=>a+b+c;// Fisrt call method make create the class callable

int call (int a,int b, int c)=>a+b+c;// Second call method

}

void main() {

var callableClassInstance = myCallableClassExample();// Creating instance of class

var callableClassReturn = callableClassInstance(5, 10, 15);

print(callableClassReturn);

}

Result:

Conclusion :

In this article, we have checked about callable classes and call() function.
Thanks for Reading.