Document persister's handling of workflow context

[ehuelsmann]

Description

Document that the serializer is expected to persist the context as well as the immediate workflow state. I'm explicitly declaring that it's not the Context instance which is to be returned, because that creates a tight coupling between the persister and the context class it will use. At a later stage, the Factory can be used to associate different Context classes with workflows.

Also, update the File persister to persist the workflow's Context according to the declared protocol.

Note: we probably needs something similar in the DBI serializer?

Type of change

• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Marking as 2.0, because this breaks older serializations: When a Context object was returned from the persister, the new context being instantiated by the Factory receives the content of the blessed Context hash instead of the PARAMS hash.

Checklist:

• My code follows the style guidelines of this project, please see the contribution guidelines.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[coveralls]

Coverage increased (+0.07%) to 92.446% when pulling 41d2438 on ehuelsmann:persister-context-docs into 8ae8d0e on jonasbn:master.

[jonasbn]

Looks good

[jonasbn]

@ehuelsmann you have marked this for 2.0 milestone, could it not be a part of the 1.58 release?

[ehuelsmann]

@jonasbn I don't think that's a good idea. I listed this as a breaking change because it changes how workflows are being serialized, which I'd expect to cause problems for people with stored contexts like the contexts stored through the 'file persister': the contract changed from returning an instantiated context to returning the keys that are to be used to instantiate a context.

In regular Perl objects, we'd be able to do %$object to get the keys we need, but with Workflow::Base that's not the case: it stores its values in PARAMS.