# Confusing about before\_filter do |controller|

**URL:** <https://www.ruby-forum.com/t/confusing-about-before-filter-do-controller/179074>\
**Category:** Rails\
**Created:** [November 17, 2009, 7:34am UTC](https://www.ruby-forum.com/t/confusing-about-before-filter-do-controller/179074 "2009-11-17T07:34:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![rubyernewbie](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/9dc877/32.png) [@rubyernewbie](https://www.ruby-forum.com/u/rubyernewbie)\
**Post date:** [November 17, 2009, 7:34am UTC](https://www.ruby-forum.com/t/confusing-about-before-filter-do-controller/179074/1 "2009-11-17T07:34:03Z")

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## so could I use a code like

## before\_filter do |controller| controller.god = “Mygod” end

and used god or @god veriable in layout?

it seems @god ok. but why it’s possible?

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<div class="post-metadata">

**Author:** ![rubyernewbie](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/9dc877/32.png) [@rubyernewbie](https://www.ruby-forum.com/u/rubyernewbie)\
**Post date:** [November 18, 2009, 9:01am UTC](https://www.ruby-forum.com/t/confusing-about-before-filter-do-controller/179074/2 "2009-11-18T09:01:12Z")

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Hi Zhenning G.

```
 From api it says before_filter accepts a block with controller 

```

passed.“The block has access to both the request and response objects  
complete with convenience methods for params, session, template, and  
assigns”. And in your case ‘god’ an instance variable which may be  
declared somewhere with attr\_writer or attr\_accessor

Sijo K George