Convenience methods for Obligation and add_observer returning self

[pitr-ch]

No description provided.

[mighe]

if Observable#add_observer returns self, we will never be able to remove an observer added as block.

x = o.add_observer { ... }
o.delete_observer(x)

I like very much a fluent interface, but in this case it will make code less flexible

[pitr-ch]

@mighe Thanks for reviewing. My thinking is: when {} it is probably just an ad hoc observer which does not need removing and reference. Objects as observers can be removed directly. There is also a way around that:

o.add_observer(&(observer = -> { 'a' }))
o.delete_observer observer
# or with Proc auto-detection
o.add_observer(observer = -> { 'a' })
o.delete_observer observer

I would allow o.add_observer(observer = -> { 'a' }) and keep returning self, also because it seems to me that observers are more often created then removed so I'd like to make creation more convenient. What do you think?

[mighe]

I still don't like the self alternative, the last syntax is somehow clumsy, personally I find it as an "advanced construct" not really easy to read, especially the one with the ampersand.
In my opinion, there's only a little improvement with the self option, but it can lead to memory leaks especially with long living entities like Agent.
For that I still prefer the "old" way, if someone wants to save some keystroke adding observers can use tap.

We're talking about personal taste, so I'd like to hear the opinion from the other team members

[pitr-ch]

Ok lets wait :) For completeness' sake this was suggested in #73 (comment) to be able to write:

actor.ask :something,
          Ivar.new.add_observer { |time, value, reason| p time, value, reason }

[pitr-ch]

Just got an idea :)

x.add_observer { 'a' } # => proc
x.with_observer { 'a' } # => x

What do you think? For me this is a winner. Keeps the old behavior and adds what is needed for convenient observer adding.

[jdantonio]

Good catch, @mighe. When @pitr-ch and I first discussed returning self I failed to consider deleting the observer. Thank you for noting this.

[jdantonio]

I've opened an Issue for tracking intermittently failing tests and I'm working through those as I find them. Please feel free to add to the list here when you experience these failures.

[pitr-ch]

@jdantonio thanks, this one is already there so I'll rerun this to get a green here.

[pitr-ch]

@mighe ack on with_observer?

[mighe]

Sorry 😊
Yes, it is fine by me, with little documentation it is very clear and unambiguous

[jdantonio]

👍

[pitr-ch]

Thanks, doc added, merging after travis pass.