Controller Instance Variables

Rails
21

On Apr 28, 4:58 pm, djolley [email protected] wrote:

using a block.
A key difference with using the block form is that (because blocks are
closures) self will be the class, not the controller instance (which
is why you get passed the controller as a parameter). For example you
can’t do

before_filter do |controller|
@val = true
end

because that will set the instance variable in the wrong object. you
could use controller.instance_variable_set but that’s just disgusting.
so you’re left with

before_filter do |controller|
controller.some_method
end
…
def some_method

end

at which point you might as well do before_filter :some_method. Plus I
like giving things names when appropriate.

Fred

22

because that will set the instance variable in the wrong object. you
could use controller.instance_variable_set but that’s just disgusting.

Well now, hold on there a minute, Fred. :slight_smile: I kind of like it. In
fact, it’s exactly what I asked for. I don’t find it all that
disgusting. Anyway, I now know how to do it both ways and I can
decide which way I like the better. Thanks to all for the input in
this topic.

      ... doug
23

Hi djolley. You can also use class variables or global variables:

test.rb:

$b=‘global value’
class MyTest
@@a=‘class value’
def class_val
@@a
end
def global_val
$b
end
end

test = MyTest.new
puts test.class_val
puts test.global_val

$ ruby test.rb
class value
global value

These variables will not be reset when a new instance is created.
Haven’t tested @@class_val in a view but it should work.

Regards,
Morgan

24

Morgan C. wrote:

Hi djolley. You can also use class variables or global variables:

test.rb:

$b=‘global value’
class MyTest
@@a=‘class value’
def class_val
@@a
end
def global_val
$b
end
end

BAD RUBY!! No global vars! Don’t even go there. That’s all I have to say
about that. :slight_smile:

25

So, I see that we have a working solution to this problem. THAT’S
GREAT NEWS! Thanks a batch for all of the contributions.

I would, however, like to see if the solution couldn’t be advanced one
step further. The methodology that we have working so far is to
define a method as a filter somewhere and then pass the name of that
method as a symbol to before_filter. Obviously, this requires a
separate definition of the method. My question is this: Can we
somehow do this whole thing in a single step by passing the
before_filter a block rather than a symbol? before_filter is supposed
to accept a block. So, conceptually, my understanding is that we
would need some code that looks something like this:

before_filter do |controller|
some_code_here
end

Can anyone please tell me what code I would need to supply as a
replacement for some_code_here in order to get this thing to work
using a block.

Thanks.

      ... doug
26

Doug J. wrote:

because that will set the instance variable in the wrong object. you
could use controller.instance_variable_set but that’s just disgusting.

Well now, hold on there a minute, Fred. :slight_smile: I kind of like it. In
fact, it’s exactly what I asked for. I don’t find it all that
disgusting. Anyway, I now know how to do it both ways and I can
decide which way I like the better. Thanks to all for the input in
this topic.

      ... doug

If you want to be a good Rails citizen, I’d recommend following Fred’s
advice. He have you a clean and conventional solution and I guarantee
you he knows what he’s talking about. I’d have given you the same advice
if the original posting was stated slightly more clearly.