Vine is a lightweight Python library that implements 'promises' for managing future evaluations and lazy computations, particularly useful in asynchronous and event-driven programming paradigms. It enhances flexibility by allowing nested promises within callbacks and error handlers. As of version 5.1.0, it is actively maintained by the Celery project.
pip install vineVerified import paths — ran on the pinned version, not inferred.
This quickstart demonstrates how to create a promise, attach success and error handlers using `.then()` and `on_error`, and then fulfill the promise with a value or an exception.
Upgrade your Python environment to 3.7 or newer to use `vine` version 5.x. Consider pinning `vine<5.0.0` if you require Python 2.x or older Python 3 versions.
Remove imports from `vine.five`. The library is now Python 3.7+ exclusive, so compatibility shims are no longer necessary.
If encountering issues after a `vine` upgrade, ensure that its primary consumers (e.g., Celery, Kombu) are also updated to their latest compatible versions. Re-installing the parent library (e.g., `pip install --upgrade celery kombu`) can often resolve implicit dependency conflicts by selecting a compatible `vine` version.
Investigate the specific code path that triggers the `ValueError('Operation failed!')`. This might involve debugging the promise fulfillment logic to understand the exact condition leading to the exception. If the error is not directly related to `vine`'s public API or its immediate dependencies, consider it an application-specific issue. If it surfaces after a `vine` upgrade, review `vine`'s release notes for subtle behavioral changes that could impact promise-related operations.Examine the traceback (if available) to pinpoint the exact source of the ValueError. Review application code paths leading to the 'Operation failed!' message. Ensure all necessary inputs are valid and operations are correctly handled. If `vine` is involved, verify its usage patterns and data inputs are correct according to its API documentation.
Install the library using pip: `pip install vine`
Use the `promise.get()` method to retrieve the result of a resolved promise (this blocks), or provide callbacks to `promise.then()` for asynchronous handling.
Provide a callable function (e.g., a lambda or a defined function) as the `callback` or `errback` argument to `then()`.
Ensure that `resolve()` or `reject()` is called only once per `vine.Promise` instance, typically by managing state or ensuring resolution logic is not triggered multiple times.
No dependency data recorded yet.