Signals

Signals are observers. They permit you to run code when a specific action is happening.

There is a lot of signal that Fabricius raises so you can subscribe to any thing you’d like. For example, before committing a file, you can add a suffix to its name before it get committed.

from fabricius.app.signals import before_file_commit
from fabricius.models.file import File

on_file_commit(file: File):
    file.name = f"{file.name}.template"

before_file_commit.connect(on_file_commit)

Here is a list of the available signals raised in Fabricius.

fabricius.app.signals.before_file_commit = <fabricius.models.signal.Signal object>

A Signal called when a File is about to commit a file.

fabricius.app.signals.on_file_commit_fail = <fabricius.models.signal.Signal object>

A Signal called when a File had an exception occurring when committing a file.

fabricius.app.signals.after_file_commit = <fabricius.models.signal.Signal object>

A Signal called when a File has committed a file.

fabricius.app.signals.before_template_commit = <fabricius.models.signal.Signal object>

A Signal called when a Template is about to commit files.

fabricius.app.signals.after_template_commit = <fabricius.models.signal.Signal object>

A Signal called when a Template has committed all the files.

Create your own signals

You can create your own signal by creating a fabricius.models.signal.Signal object and letting it available in your project.

from fabricius.models.signal import Signal

my_signal = Signal()

While this is totally OK to go like this, you can also optionally type the .send()/.connect() methods by providing a function. Fabricius will extract the function’s signature and use it to transfer the arguments into the signal’s methods.

from fabricius.models.file import File
from fabricius.models.signal import Signal

def my_signal_hint(file: File):
    ...

my_signal = Signal(func_hint=my_signal_hint)

my_signal.send(File("test.py"))  # This is OK
my_signal.send()  # This is not! Your type checker will complain!

# Good
def signal_receiver(file: File):
    ...
my_signal.connect(signal_receiver)

# Bad
def signal_receiver(receiving_file: File):
    ...
my_signal.connect(signal_receiver)

# This will raise a type error if the function's signature is altered
# (New, removed, renamed arguments, etc...)