Multiple from/to in transition definition block

[marclennox]

Is there a way to specify an array of from: or to: states in the transition definition block? If not are you open to a PR?

[marclennox]

I'm looking at the code and it seems that you do support an array for the to: state but not from: and it looks like an easy change in the callback.rb file to allow this.

[greysteil]

I think this has been discussed before, and we decided that having array-to-array callbacks could be confusing. @hmarr - do you have the context?

[hmarr]

Yes, there was a long discussion about this in #95.

This comment describes the original reasoning. We actually initially allowed arrays for both :from and :to, but found the resulting code pretty unclear.

@marclennox it's probably worth starting by having a skim through #95. After that, if you've got a good example of where supporting a :from array would be beneficial, we can revisit. Otherwise I'd rather stick with the current decision.

[marclennox]

Thanks @hmarr. I recently moved away from the state_machine gem to statesman and statesman-events and was trying to keep the logic as close to the same as possible.

I use the events module and have a few cases where different events transition to the same 'to' state, but from different 'from' states. Depending on the event that triggered the transition, I may have different logic in after_transition when transitioning from one of the 'from' states, but for the others it's the same logic. For the 'others' that have the same logic, I now need to duplicate the code in multiple after_transition blocks.

Perhaps this is not a proper use of a state machine, but this is how I did it with state_machine which did support this use-case.

Alternatively, is there a way I can get access to the triggering event or the 'from' state from within the after_transition block?

I was able to make the code change to statesman quite easily, it was obvious that multiple from states had been previously supported.