Yes this does explain alot. I tried the command that you recommended:
if tier.nil?
set :tier, "sandbox"
end
But I got an exception that states that the variable "tier" does not exsist in the Capistrano:Configuration Object. To get around the problem I am using ENV variables right now. But would much rather use the command line. Any ideas?
Orion Delwaterman
On 11/2/06, Jamis Buck <[EMAIL PROTECTED]> wrote:
Ah, this is a subtle one. You're running into an aspect of how Ruby
deals with local variables. What you want is to use set(), instead of
assignment, since variables in capistrano are not really Ruby
variables. Try this:
if tier.nil?
set :tier, "sandbox"
end
That should do the trick. Now, if you're curious about the behavior
you saw, read on:
First, a simple example. Suppose you have the following Ruby script:
p x
If you execute that command, you'll get an exception, "undefined
local variable or method `x'". However, if you do something like this:
if false
x = "hello"
end
p x
You'll now get the output 'nil'. Even though x is never explicitly
set! This is because Ruby will silently vivify x, due to its
reference in the body of the if.
Now, Capistrano handles variables specially. It actually keeps a hash
of key/value pairs, and uses method_missing to hook into that. Thus,
your capistrano script can say:
p tier
and have it just work, even though you do not explicitly set tier as
a local variable. So, let's look at your example:
p tier #-> gives 'dev'
if tier.nil? #-> this is false
tier = 'sandbox'
end
p tier #-> gives 'null'
The first line works in capistrano, not because tier is a local
variable, but because of method_missing. The local variable is not
actually defined, so method_missing gets called, which looks up the
variable and returns the value.
Ditto for the condition in the if clause.
However, you are setting a local variable in the body of the if,
which causes ruby to implicitly vivify 'tier' as a local variable,
with a value of nil. The next time you ask for 'tier', that local
variable is used, and method_missing does not get called.
Hope that makes sense,
Jamis
On Nov 2, 2006, at 9:12 AM, [EMAIL PROTECTED] wrote:
>
> I am trying to write my deploy script that will work for multiple
> deployment environments (sandbox, dev, staging, production). While
> working on this I ran into a problem with variable assignment. I
> wrote
> some debug scripts to check on somethings and got the strangest
> results. Here is what I wrote in my deploy.rb:
>
> puts "tier: #{tier}" if !tier.nil?
> puts tier.nil?.to_s
> puts "tier: #{tier}" if !tier.nil?
> puts tier.nil?.to_s
> if tier.nil?
> tier = 'sandbox'
> end
> puts "tier: #{tier}"
> #puts "ENV[]: " + ENV["TIER"] if !ENV["TIER"]
> raise "stop"
>
> I then run the following command from my command line:
> cap -S tier=dev deploy
>
> This is what is outputted to my console:
> C:\Ruby\InstantRails\rails_apps\video_content_manager>cap -S tier=dev
> deploy
> loading configuration
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capis
> trano-1.2.0/lib/capistrano/recipes/standard.rb
> loading configuration ./config/deploy.rb
> loading configuration
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/mongr
> el_cluster-0.2.0/lib/mongrel_cluster/recipes.rb
> tier: dev
> false
> tier: dev
> false
> tier:
> ./config/deploy.rb:35:in `load': stop (RuntimeError)
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano-1.2.0/l
> ib/capistrano/configuration.rb:146:in `load'
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano-1.2.0/l
> ib/capistrano/configuration.rb:125:in `load'
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano-1.2.0 /l
> ib/capistrano/configuration.rb:125:in `load'
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano-1.2.0/l
> ib/capistrano/cli.rb:252:in `execute_recipes!'
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano-1.2.0/l
> ib/capistrano/cli.rb:252:in `execute_recipes!'
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano- 1.2.0/l
> ib/capistrano/cli.rb:233:in `execute!'
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano-1.2.0/l
> ib/capistrano/cli.rb:12:in `execute!'
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano-1.2.0/b
> in/cap:11
> from C:/Ruby/InstantRails/ruby/bin/cap:18
>
> As you can see on the last line before the exception is thrown the
> variable tier suddenly goes to nil. If I then comment out the
> following line:
>
> if tier.nil?
> # tier = 'sandbox'
> end
>
> I get the following output:
>
> C:\Ruby\InstantRails\rails_apps\video_content_manager>cap -S tier=dev
> deploy
> loading configuration
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capis
> trano-1.2.0/lib/capistrano/recipes/standard.rb
> loading configuration ./config/deploy.rb
> loading configuration
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/mongr
> el_cluster-0.2.0/lib/mongrel_cluster/recipes.rb
> tier: dev
> false
> tier: dev
> false
> tier: dev
> ./config/deploy.rb:35:in `load': stop (RuntimeError)
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano-1.2.0/l
> ib/capistrano/configuration.rb:146:in `load'
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano-1.2.0/l
> ib/capistrano/configuration.rb:125:in `load'
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano-1.2.0 /l
> ib/capistrano/configuration.rb:125:in `load'
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano-1.2.0/l
> ib/capistrano/cli.rb:252:in `execute_recipes!'
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano-1.2.0/l
> ib/capistrano/cli.rb:252:in `execute_recipes!'
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano- 1.2.0/l
> ib/capistrano/cli.rb:233:in `execute!'
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano-1.2.0/l
> ib/capistrano/cli.rb:12:in `execute!'
> from
> C:/Ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/capistrano-1.2.0/b
> in/cap:11
> from C:/Ruby/InstantRails/ruby/bin/cap:18
>
> The problem has disappeared. It seems like capistrano is doing
> something weird for an assignment to a local variable that it should
> not even be executing. Please Help!?!?!?
>
>
> [EMAIL PROTECTED]
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- [Capistrano] Local Variable Problems [EMAIL PROTECTED]
- [Capistrano] Re: Local Variable Problems Jamis Buck
- [Capistrano] Re: Local Variable Problems V. Orion Delwaterman
- [Capistrano] Re: Local Variable Problems Jamis Buck
