First steps

The simplest example could look like this:

from power_events import EventResolver

app = EventResolver()

@app.equal("type", "power-event")
def handle_example(event):
    return "Hello from power-event type event"


print(app.resolve({"type": "power-event"}))
# ["Hello from power-event type event"]

Recap, step by step

Step 1: create an EventResolver

from power_events import EventResolver

app = EventResolver()

@app.equal("type", "power-event")
def handle_example(event):
    return "Hello from power-event type event"


print(app.resolve({"type": "power-event"}))
# ["Hello from power-event type event"]

Here app will be an instance of EventResolver, it's the main entrypoint to define our event routes.

Step 2: create an event route operation

Path

"Path" here refers to our condition path, it's the path of our value inside the event.

Condition operation

"Operation" can be either built-in operation like one of:

• equal
• one_of
• contain

Or custom passing ours with when.

Define our route

from power_events import EventResolver

app = EventResolver()

@app.equal("type", "power-event")
def handle_example(event):
    return "Hello from power-event type event"


print(app.resolve({"type": "power-event"}))
# ["Hello from power-event type event"]

@app.equal("type", "power-event") tells at Power-Events that the function defines below to be triggered if an event with the value at path type is equals at power-event.

About @decorator

the @ syntax in Python is called a "decorator".

It's a shorthand to decorator(function).

A decorator is a function that takes a function to do something with it.

In our case, it registers the function in our Resolver, that way it will be called corresponding to the condition given. Here when 'type' is equal to 'power-event'.

Function constraint

from power_events import EventResolver

app = EventResolver()

@app.equal("type", "power-event")
def handle_example(event):
    return "Hello from power-event type event"


print(app.resolve({"type": "power-event"}))
# ["Hello from power-event type event"]

Currently, there is a one constraint on the function handler signature, it should have as first argument the event.

Otherwise, a TypeError will occur saying an argument was passed.