Singleton classes

Testing RSpec
1

Hello
I am trying to spec a singleton ruby class,
And I am having a little trouble because my specs are not more isolated,
as I am getting the same instace of the class for all my examples.

How should I do this.?
Which is the correct way of specing a singleton class?

Thanks
Juanma

2

On Tue, Jan 19, 2010 at 6:03 AM, Juanma C. [email protected]
wrote:

Hello
I am trying to spec a singleton ruby class,
And I am having a little trouble because my specs are not more isolated,
as I am getting the same instace of the class for all my examples.

How should I do this.?
Which is the correct way of specing a singleton class?

I’m assuming you mean singleton as in the Singleton Pattern, as
opposed to the singleton class of an object, yes?

If so, you’ll have to dup it or subclass it in your spec if you want
to isolation.

Why do you need a Singleton, though?

David

3

Yes, I mean the Singleton Pattern.
I am not an expert with OO, but I supposed this pattern was what best
fits my needs of a class that represent a unique resource in the system,
in this case it’s something like a queue of jobs that I have to
administrate in real time.
Am I right?
Maybe not, because I am writing a web app and not using globals or
session state to store this class, and I am accessing the instance of
the class in each http request.
In that case the dup option sounds good for me.
But what do you think?
Thanks David

Juanma

David C. wrote:

On Tue, Jan 19, 2010 at 6:03 AM, Juanma C. [email protected]
wrote:

Hello
I am trying to spec a singleton ruby class,
And I am having a little trouble because my specs are not more isolated,
as I am getting the same instace of the class for all my examples.

How should I do this.?
Which is the correct way of specing a singleton class?

I’m assuming you mean singleton as in the Singleton Pattern, as
opposed to the singleton class of an object, yes?

If so, you’ll have to dup it or subclass it in your spec if you want
to isolation.

Why do you need a Singleton, though?

David

4

On Jan 19, 2010, at 2:33 pm, Juanma C. wrote:

Yes, I mean the Singleton Pattern.
I am not an expert with OO, but I supposed this pattern was what best
fits my needs of a class that represent a unique resource in the system,
in this case it’s something like a queue of jobs that I have to
administrate in real time.
Am I right?

What would be the implications of not using a singleton? Bear in mind
that if you’re writing a webapp, you will at some point have two of
these objects simultaneously in different processes.

What is the responsibility of the object itself, and where does the
responsibility for enforcing that the resource is only used by one
client at a time live?

Ashley

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