merge_callbacks

def merge_callbacks(
    callbacks: CallbacksType,
) -> None:

Parameter	Type	Description
callbacks	CallbacksType	A single Callback object or an iterable of Callback objects to merge into the global registry.

Introduction

swanlab.merge_callbacks() merges custom callbacks into the global SwanLab callback registry. This allows you to register callbacks before calling swanlab.init(), enabling plugin injection in frameworks where swanlab.init() is not directly accessible (e.g., when using SwanLab with Transformers).

TIP

merge_callbacks must be called before swanlab.init(). It will raise a RuntimeError if called while a run is active.

Usage

Single Callback

import swanlab
from swanlab import Callback

class MyCallback(Callback):
    @property
    def name(self):
        return "my_callback"

    def on_run_initialized(self, run_dir, path, **kwargs):
        print("Run initialized!")

swanlab.merge_callbacks(MyCallback())
swanlab.init(project="my-project")

Multiple Callbacks

Pass a list to merge multiple callbacks at once:

import swanlab
from swanlab import Callback

class MyCallback(Callback):
    @property
    def name(self):
        return "my_callback"

    def on_run_initialized(self, run_dir, path, **kwargs):
        print("Run initialized!")

class AnotherCallback(Callback):
    @property
    def name(self):
        return "another_callback"

    def on_run_initialized(self, run_dir, path, **kwargs):
        print("Run initialized by another callback!")

swanlab.merge_callbacks([MyCallback(), AnotherCallback()])
swanlab.init(project="my-project")

Callback Lifecycle

SwanLab callbacks implement the Callback base class. Common hook methods include:

• on_run_initialized(run_dir, path, **kwargs) — Called when a run is initialized.
• on_run_finished(state, error) — Called when a run finishes.