constants already initialized warnings

rubyonrails-talk
1

I have some constants defined in my application_helper.rb and I keep getting these warning: already initialzed constant ________

I greped my project and made sure these constants are not defined or set elsewhere. is my application_helper being loaded multiple times?

2

You should check if it's defined using defined?.

For example, you'll see something like this in your environment.rb:

RAILS_GEM_VERSION = '1.2.6' unless defined? RAILS_GEM_VERSION

3

thanks, that got rid of the warnings.

still it suggests my application_helper.rb is being loaded multiple times per request. is that normal? doesn't seem efficient.

4

Not multiple times per request, but rather reloaded per request. The first request may be fine, but subsequent requests will show that error. A constant is exactly that: a constant variable for the life of your application. If you’re defining constants in your application_helper, maybe you should be doing it somewhere else?

5

No, no, you shouldn't be throwing any defined? like that. One uses defined? when it makes sense in her context, not to hide a suspicious behaviour.

What you are seeing is something that shouldn't happen, so the right thing to do is to discover why it is happening and fix it.

I think a trick to debug that could be to throw

     RAILS_DEFAULT_LOGGER.debug(caller.join("\n")) if defined? SOME_CONSTANT      SOME_CONSTANT = value

in the helper module. There we use defined? to print the execution stack just in the second run.

-- fxn

6

Not multiple times per request, but rather reloaded per request. The first request may be fine, but subsequent requests will show that error. A constant is exactly that: a constant variable for the life of your application. If you're defining constants in your application_helper, maybe you should be doing it somewhere else?

But this is not the case with application_helper.rb, in the sense that ApplicationHelper is autoloaded:

     $ script/console      Loading development environment (Rails 2.0.2)      >> Dependencies.autoloaded? ApplicationHelper      => true

That is a side-effect of prepare_application.

So, you know, you get a fresh new module in the fresh new constant ApplicationHelper per request in development mode. Any nested constant is new in consequence, hence if everything is set up as usual you don't get those warnings.

-- fxn