README.md

Actions

Declarative steps.

Actions allows you to define consecutive steps in a declarative manner.

Basic example:

from actions import action, Action, Actions

@action(label="Step 1")
def step_1():
    print "This is step 1"

@action(label="Step 2")
def step_2():
    print "This is step 2"

actions = Actions(
    Action(step_1),
    Action(step_2)
)

actions()

# Outputs:
## This is step 1
## This is step 2

Each action must be decorated with @action. The label of a decorated action can later be retrieved for better outputting.

Passing arguments

from actions import action, Action, Actions

@action(label="Step")
def step(n):
    print "This is step %s" % n

actions = Actions(
    Action(step, 1),
    Action(step, 2)
)

actions()

# Outputs:
## This is step 1
## This is step 2

Passing state

from actions import action, Action, Actions, State, StatefulAction

@action(label="Pre-step")
def pre_step(n, result_store):
    print "This is prestep %s"

    result_store.calculation = n * 10

def step(calculation):
    print "Result from calculation: %s" % calculation

actions = Actions(
    StatefulAction(pre_step, 1, state=["calculation"]),
    Action(step, State("calculation"))
)

actions()

# Outputs:
## This is prestep 1
## Result from calculation: 10

Enabling / disabling actions

from actions import action, Action, Actions, State, StatefulAction

@action(label="Step 1")
def step_1():
    print "This is step 1"

@action(label="Step 2")
def step_2(result_store):
    print "This is step 2"
    result_store.enabled_step_3 = False

@action(label="Step 3")
def step_3():
    print "This is step 3"

@action(label="Step 4")
def step_4():
    print "This is step 4"

actions = Actions(
    Action(step_1, enabled=False),
    StatefulAction(step_2, state=["enabled_step_3"]),
    Action(step_3, enabled=State("enabled_step_3")),
    Action(step_4)
)

actions()

# Outputs:
## This is step 2
## This is step 4

Failing actions

You can fail individual actions by returning False:

from actions import action, Action, ActionFailed, Actions

@action(label="Step 1")
def step_1():
    print "This is step 1"
    return False

@action(label="Step 2")
def step_2():
    print "This is step 2"

actions = Actions(
    Action(step_1),
    Action(step_2)
)

try:
    actions()

except ActionFailed, action_failed:
    print "%s failed" % action_failed.label

# Outputs:
## This is step 1
## Step 1 failed

Action can also fail if they throw exceptions:

from actions import action, Action, ActionFailed, Actions

@action(label="Step 1")
def step_1():
    print "This is step 1"
    a[0] = True # Reference error

@action(label="Step 2")
def step_2():
    print "This is step 2"

actions = Actions(
    Action(step_1),
    Action(step_2)
)

try:
    actions()

except ActionFailed, action_failed:
    print "%s failed" % action_failed.label

# Outputs:
## This is step 1
## Step 1 failed

Cleaning up

from actions import action, Action, ActionFailed, Actions

@action(label="Step 1")
def step_1():
    print "This is step 1"
    a[0] = True # Reference error

@action(label="Cleanup")
def cleanup():
    print "Cleaning up"

actions = Actions(
    Action(step_1),
    Action(cleanup, _finally=True)
)

try:
    actions()

except ActionFailed, action_failed:
    print "%s failed" % action_failed.label

# Outputs:
## This is step 1
## Cleaning up
## Step 1 failed

When an exception occurs within an action, the exception is logged to the actions package logger.

Getting Started

To install, cd into the actions directory (where this README is located) then run:

$ pip install .

Actions requires Python version 2.7.

If you're not running in a VM or container, it's best to run inside of a virtual environment (if you have virtualenv installed):

$ virtualenv venv
$ source venv/bin/activate
$ pip install .