On 21/05/11 5:49 AM, Gazzy wrote:
Does anyone know how to get Ruby/Sinatra models to execute initialize
methods within DataMapper models?
I am trying to add a Mutex class variable
your code is adding an *instance* variable, they are very different things.
to one of my Datamapper
classes so I can syncronize access to some of the methods but I am
getting the error - undefined method `synchronize' for nil:NilClass
My code looks like ...
class Booking
include DataMapper::Resource
...
def initialize(app, options)
super
@lock = Mutex.new
end
...
def take_slot
# Record there is 1 less available slot
@lock.synchronize do
...
end
end
but the initialize class never gets called. All the mutex examples on
the internet don't use Datamapper models.
I started with a simple
def initialize
super
@lock = Mutex.new
end
then I realised that DataMapper probably has a more complex set of
parameters for the initialise function. Hours of googling led me to
the above code but any help much appreciated. I haven't yet figured
out how to look into gems to see what is going on under the hood.
There is an old note related to this but I don't understand the
solution proposed.
http://datamapper.lighthouseapp.com/projects/20609/tickets/1043-datamapperresource-is-not-calling-initialize-definined-in-models
I've had to bodge it for now with code like
def take_slot
if !defined?(@lock)
@lock = Mutex.new
end
# Record there is 1 less available slot
@lock.synchronize do
...
end
This doesn't answer your question, but:
def lock
@lock ||= Mutex.new
end
def take_slot
lock.synchronize do
...
end
end
is not so ugly.
but its ugly :-( Any help much appreciated.
I also tried posting on the Sinatrarb Google group but no joy there.
What is the actual problem you are trying to solve? I have a suspicion
Mutex doesn't do what you think it does in this context.
Cheers,
Xavier
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