# Why is extending MovieClip class different?

**URL:** <https://forum.kirupa.com/t/why-is-extending-movieclip-class-different/231930>\
**Category:** flash\
**Created:** [July 9, 2007, 6:21pm UTC](https://forum.kirupa.com/t/why-is-extending-movieclip-class-different/231930 "2007-07-09T18:21:27Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![ironchefmoto](https://avatars.discourse-cdn.com/v4/letter/i/91b2a8/32.png) [@ironchefmoto](https://forum.kirupa.com/u/ironchefmoto)\
**Post date:** [July 9, 2007, 6:21pm UTC](https://forum.kirupa.com/t/why-is-extending-movieclip-class-different/231930/1 "2007-07-09T18:21:27Z")

</div>

I’ve been going through the OOP AS 2.0 tutorial here on Kirupa, and I was curious WHY this code is in a class which extends the MovieClip class and is used to affect a linkage item in the library:

```auto
// init method for arguments which in other normal
    // circumstances (non-MovieClip classes) would be
    // given to the constructor. Not an option with MovieClips
    function init (pGravity:Number, pBoundries:Object) {
        gravity = pGravity;
        boundries = pBoundries;
        return this;
    }

```

Is there something undocumented about why I wouldn’t pass those parameters in when instantiating a new instance of the class in question? What is different about extending the MovieClip class?

Thanks,  
IronChefMorimoto