manifold.lifecycle — spootnik/maniflow 0.1.8

Convention based lifecycle management of asynchronous chains. This implements a lightweight take on the ideas behind interceptors and similar libraries.

Notable differences are:

• Manifold is the sole provided execution model for chains
• No chain manipulation can occur
• Guards and finalizer for steps are optional
• Exceptions during lifecycle steps stop the execution

error-handlers-for clj

(error-handlers-for id handlers)

A list of error handlers to try in sequence for a specific stage

prepare-stage clj

(prepare-stage stage opts steps error-handlers)

Prepare a single stage, discard steps which do not have a handler for a specific stage.

run clj

(run init steps)

(run init opts steps)

Run a series of potentially asynchronous steps in sequence on an initial value (init0, threading each step's result to the next step as input.

Steps are maps or the following keys:

[:id :enter :leave :in :out :discard? :guard]

• id is the unique ID for a step
• enter is the function of the previous result in the enter stage
• leave is the function of the previous result in the leave stage
• in when present determines which path in the context will be fed to the handler. The handler is considered a function of the contex
• out when present determines which path in the context to associate the result to, otherwise replaces the full context
• discard? when present, runs the handler but pass the context untouched to the next step
• guard is an optional predicate of the current context and previous preventing execution of the step when yielding false

In the three-arity version, an extra options maps can be provided, with the following keys:

[:augment :executor :initialize :stop-on]

• augment is a function called on the context for each step, expected to yield an updated context. This can useful to perform timing tasks
• executor a manifold executor to execute deferreds on
• initialize is a function called on the context before running the lifecycle.
• out a path in the context to retrieve as the final value out of the lifecycle
• stop-on predicate which determines whether an early stop is mandated, for compatibility with interceptors terminate-when is synonymous.

stages clj

Fixed list of stages to run through

step clj

(step enter)

(step id handlers & {:as params})

Convenience function to build a step map. Requires and ID and handler, and can be fed additional options

step* clj

(step* id handlers {:keys [in out lens guard discard? error]})

Convenience function to build a step map. Requires and ID and handler, and can be fed additional options