# multiple constructor, how to do with the factory method and itknewmacro

**URL:** https://discourse.itk.org/t/multiple-constructor-how-to-do-with-the-factory-method-and-itknewmacro/968
**Category:** Beginner Questions
**Created:** [May 31, 2018, 9:10pm UTC](https://discourse.itk.org/t/multiple-constructor-how-to-do-with-the-factory-method-and-itknewmacro/968 "2018-05-31T21:10:28Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![pdeman](https://discourse.itk.org/letter_avatar_proxy/v4/letter/p/9fc348/32.png) [@pdeman](https://discourse.itk.org/u/pdeman)
#### Post date: [May 31, 2018, 9:10pm UTC](https://discourse.itk.org/t/multiple-constructor-how-to-do-with-the-factory-method-and-itknewmacro/968/1 "2018-05-31T21:10:28Z")

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Hi,

I have never used factory method before and I am a little lost.

I want to define a second constructor with different input parameters.

the constructor is called when calling ::New() ?  
how do I pass the constructor parameters when using ::New ?

Regards

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### Author: ![dzenanz](https://discourse.itk.org/user_avatar/discourse.itk.org/dzenanz/32/1093_2.png) [@dzenanz](https://discourse.itk.org/u/dzenanz)
#### Post date: [May 31, 2018, 9:14pm UTC](https://discourse.itk.org/t/multiple-constructor-how-to-do-with-the-factory-method-and-itknewmacro/968/2 "2018-05-31T21:14:19Z")

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`New()` only works with default constructor. Which means if you want to use `itkNewMacro` your class must have to be able to accept important parameters via methods, as you can’t pass them into a constructor.