class form_field_base {
    // Lots of code
}
class form_field_text extends form_field_base {
    // Lots of code
}
class form_field_email extends form_field_text {
    // Extending the text object to update validation, and set input type="email"
}
class form_field_file extends form_field_base {
    // Lots of code, for example uploading files
}

class form_field_base_common {
    // Lots of code
}
class form_field_base extends form_field_base_common {
    // By default is empty
}

class form_field_text_common extends form_field_base {
    // Lots of code
}
class form_field_text extends form_field_text_common {
    // ...
}

class form_field_email_common extends form_field_text {
    // Extending the text object to update validation, and set input type="email"
}
class form_field_email extends form_field_email_common {
    // ...
}

class form_field_file_common extends form_field_base {
    // Lots of code, for example uploading files
}
class form_field_file extends form_field_file_common {
    // ...
}

A <- B <- C

A->a()
B->a(), B->b()
C->a(), C->b(), C->c()

A1 <- B <- C

A1->a(), A1->a1(),
B->a(), B->a1(), B->b()
C->a(), C->a1(), C->b(), C->c()

A1 decorates A
B1 decorates B
C1 decorates C

A1 <- B1 <- C1

A1->a1()
B1->a1()
C1->a1()

A1 hosts a reference of A
B1 hosts a reference of B
C1 hosts a reference of C

A1->a() ----> $this->myA->a();
B1->a() ----> $this->myB->a();
B1->b() ----> $this->myB->b();

A1->a1() ----> $this->a1();

A1 instead of A
B1 instead of B
C1 instead of C

abstract class FormComponent {
    public __construct(FormField $field) {
        $this->_field = $field;
    }

    public html() {
        // Here you can choose any way to integrate the field's input HTML into
        // the component's HTML. You can wrap it in a label, for example.
        return $self->_get_html() . $self->_field->html_input();
    }
}

$field = new form_field_email($arguments); // Whatever arguments it takes

// Here the FormComponent_Email class inherits the FormComponent class
$component = new FormComponent_Email($field);
$component->set_hint('Some hint'); // Set your help text here
$component->set_label('Enter your email');

// You can even add an error container if you wish
if ($some_email_error) {
    $component->set_error('Your email has an error!');
}

$component_html = $component->html();