# Consts for symbols or too anal?

**URL:** <https://www.ruby-forum.com/t/consts-for-symbols-or-too-anal/155521>\
**Category:** Rails\
**Created:** [December 12, 2008, 9:00pm UTC](https://www.ruby-forum.com/t/consts-for-symbols-or-too-anal/155521 "2008-12-12T21:00:40Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![jbell38](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/edb3f5/32.png) [@jbell38](https://www.ruby-forum.com/u/jbell38)\
**Post date:** [December 12, 2008, 9:00pm UTC](https://www.ruby-forum.com/t/consts-for-symbols-or-too-anal/155521/1 "2008-12-12T21:00:40Z")

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Soliciting some opinions here.

I keep having this urge to create constants for some of my symbol  
keys, so the Ruby interpreter catches my typos. I’m wondering how  
other developers handle this / what Rails best practices are.

The urge is strong for keys that are shared between lots of  
controllers and views. E.g., instead of flash[:warning], I want to use  
flash[WARNING] and make a WARNING=:warning const that’s included in  
ApplicationController and ApplicationHelper. I have some “global”  
param names I also want to do this for, like the sort column and  
“redirect back” URL (which are handled by ApplicationController  
methods and used in lots of templates).

I hesitate to do this because I’ve never read a code example that does  
it. And of course I could take it to a ridiculous extreme by consting  
every param name in every form, so there has to be balance and  
discretion.

So should I do this? Or is the Rails way to stick with :warning and  
use tests to catch my typos? Exhaustive testing seems kinda infeasible  
for this. Like, I have a lot of error paths with a lot of different  
flash error messages, and I have a lot of candidate columns to sort  
by. But maybe I’m just lazy.

Thanks,  
Jeff

---

<div class="post-metadata">

**Author:** ![jbell38](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/edb3f5/32.png) [@jbell38](https://www.ruby-forum.com/u/jbell38)\
**Post date:** [December 14, 2008, 8:28pm UTC](https://www.ruby-forum.com/t/consts-for-symbols-or-too-anal/155521/2 "2008-12-14T20:28:55Z")

</div>

Jeff B. wrote:

> Soliciting some opinions here.
> 
> I keep having this urge to create constants for some of my symbol  
> keys, so the Ruby interpreter catches my typos. I’m wondering how  
> other developers handle this / what Rails best practices are.
> 
> The urge is strong for keys that are shared between lots of  
> controllers and views. E.g., instead of flash[:warning], I want to use  
> flash[WARNING] and make a WARNING=:warning const that’s included in  
> ApplicationController and ApplicationHelper. I have some “global”  
> param names I also want to do this for, like the sort column and  
> “redirect back” URL (which are handled by ApplicationController  
> methods and used in lots of templates).
> 
> I hesitate to do this because I’ve never read a code example that does  
> it. And of course I could take it to a ridiculous extreme by consting  
> every param name in every form, so there has to be balance and  
> discretion.
> 
> So should I do this? Or is the Rails way to stick with :warning and  
> use tests to catch my typos? Exhaustive testing seems kinda infeasible  
> for this. Like, I have a lot of error paths with a lot of different  
> flash error messages, and I have a lot of candidate columns to sort  
> by. But maybe I’m just lazy.
> 
> Thanks,  
> Jeff

Hi Jeff,

I would prefer to write methods to encapsulate the behavior, and if you  
mistype a method name you’ll get a NoMethodError. You can put this in  
application.rb:

def flash\_warning(msg)  
flash[:warning] = msg  
end

Then just call:

flash\_warning ‘hello’

With a little metaprogramming you could DRYly generate methods for other  
flash levels that you want to use:

%w(info warning error).each do |level|  
define\_method “flash\_#{level}” do |msg|  
flash[level.to\_sym] = msg  
end  
end