# Why use \_\_FILE\_, \_\_LINE\_\_ in class\_eval?

**URL:** <https://www.ruby-forum.com/t/why-use-file-line-in-class-eval/147821>\
**Category:** Ruby\
**Created:** [September 5, 2008, 5:54pm UTC](https://www.ruby-forum.com/t/why-use-file-line-in-class-eval/147821 "2008-09-05T17:54:02Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![benjohnson](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/3ec8ea/32.png) [@benjohnson](https://www.ruby-forum.com/u/benjohnson)\
**Post date:** [September 5, 2008, 5:54pm UTC](https://www.ruby-forum.com/t/why-use-file-line-in-class-eval/147821/1 "2008-09-05T17:54:02Z")

</div>

I’ve noticed in code that some people do:

class\_eval src

amd some do

class\_eval src, **FILE** , **LINE**

What exactly is the difference and why should I use one over the other?

Thanks for your help.

---

<div class="post-metadata">

**Author:** ![benjohnson](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/3ec8ea/32.png) [@benjohnson](https://www.ruby-forum.com/u/benjohnson)\
**Post date:** [September 5, 2008, 5:58pm UTC](https://www.ruby-forum.com/t/why-use-file-line-in-class-eval/147821/2 "2008-09-05T17:58:46Z")

</div>

On Sep 5, 2008, at 9:48 AM, Ben J. wrote:

> Thanks for your help.

raise an error inside the eva’d code and see

a @ [http://codeforpeople.com/](http://codeforpeople.com/)