tobgu/pyrsistent

Public introspection API for fields and checked types

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#47 opened on Aug 11, 2015

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 (4 comments) (0 reactions) (0 assignees)Python (1,943 stars) (141 forks)batch import
enhancementhelp wanted

Description

We're about to add some code that introspects pyrsistent classes - in particular PRecord/PClass and the checked data structures - in order to detect changes to our pyrsistent-based configuration model. You can see a sketch of this code here: https://github.com/ClusterHQ/flocker/pull/1836/files#diff-c03885f8c4e64651ea9a499e99090a83R28

Unfortunately this currently requires using private pyrsistent APIs. It would be good to have a public API for finding this information. As a first pass it seems that adding this as extra methods to the classes themselves is problematic, insofar as it means subclasses get extra methods they weren't expecting. So maybe there should be a set of public external functions that extract information from the private implementation details.

Contributor guide

Tech stack
python
Domain
backend
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Python basicspyrsistent library knowledge
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Review the linked PR (https://github.com/ClusterHQ/flocker/pull/1836/files) to understand the required introspection. Examine the private APIs currently used, such as ' fields' and ' types', in pyrsistent classes. Propose a set of public functions (e.g., 'get fields(cls)', 'get checked types(cls)') that expose this information without polluting the class interface. Ensure backward compatibility and document the new API.