Question

DRY – Don’t Repeat Yourself

ControlSignUp and ControSignIn are nearly identical. I’ve commented a “here” on the only 4 lines which are different. How can I combine this common functionality?

Actually it seem obvious..I can just pass in a single variable through the constructor…just a sec.

Answer:

 /**
 *      ControlSign
 */

var ControlSign = function( type ) 
{
    var form_element = document.getElementById( type ); 
    var response_element = document.getElementById( type + '_response' ); 
    var text_object = new Text( form_element );
    var message_object = new Message( response_element );

    this.invoke = function( ) 
    {
        if( Global.validate_input_on === 1 )
        {
            if( !text_object.checkEmpty() ) 
            {
                message_object.display( 'empty' );
                return false;
            }
            if( type === 'signup' && !text_object.checkPattern( 'name' ) ) 
            {
                message_object.display( 'name' );
                return false;
            }
            if( !text_object.checkPattern( 'email' ) ) 
            {
                message_object.display( 'email' );
                return false;
            }
            if( !text_object.checkPattern( 'pass' ) ) 
            {
                message_object.display( 'pass' );
                return false;
           }
        }
        AjaxNew.repeatUse( ajaxSerialize( form_element ) + '&ajax_type=' + type + '_control', function( server_response_text ) { ajaxType( server_response_text, response_element, 'respond' ); } );
    }
};

ControlSign.in = function()
{
    new ControlSignIn( 'signin' ).invoke();
};
ControlSign.up = function()
{
    new ControlSignUp( 'signup' ).invoke();
};

Answer 1

Simple solution: Make it a function ControlSign with a parameter, invoked with "in" or "up". You could call this “factory pattern”.

Complex solution: you use a factory function to create the two constructors. OK, what I meant is the use of a closure to create constructors:

function makeControlSign(type) {
    function constructor(...) {
        this.invoke = function(){...};
        // use the variable "type" where needed
        ...
     }
     constructor[type] = function(){...};
     return constructor;
}
var ControlSignUp = makeControlSign("up");
var ControlSignIn = makeControlSign("in");

I guess this should neither be called “factory pattern” nor “abstract factory pattern”.