Can a function from another class be passed to a custom widget in Flutter?

I have a widget called BotonEnviar used to launch custom functions when tapped:

class BotonEnviar extends StatelessWidget {
   BotonEnviar({Key? key, required this.funcion, required this.texto}) : super(key: key);

  final void Function() funcion;
  final String texto;

  @override
  Widget build(BuildContext context) {
    return Container(
      height: 40,
      width: 180,
      child: ElevatedButton(
        onPressed: () {
          print("pulsado enviar visto en el widget del boton");
          this.funcion;

        },
        child: Text(
          '${this.texto}' ,
          style: TextStyle(color: Colors.white,fontSize: 18),
        ),
      ),
    );
  }
}

And here you have a class that uses BotonEnviar:

...
SizedBox(
                      height: 15,
                    ),
                    BotonEnviar(funcion: () {
                      print("pulsado boton");

                      PublicarTema().publicarTema(temaController.text);
                    }, texto: 'Enviar',
                    ),

...

In this case, what I need is to execute PublicarTema().publicarTema(temaController.text);
when BotonEnviar is clicked.

Here you have PublicarTema() class:

class PublicarTema {



  publicarTema(String titulo){
    
    //accion al pulsar boton ENVIAR
    print("itulo recibido ${titulo}");

  }
}

I guess I am not implementing anything as I should. What I want is to keep a clean code in my app.

What I am getting after clicking on BotonEnviar is only the output from:

print("pulsado enviar visto en el widget del boton");

and not the output from

print("itulo recibido ${titulo}");

What should I change?