Minutes 2022-02-12

In S7: An Object Oriented System Meant to Become a Successor to S3 and S4

Process check-in

Minor stuff I'm just doing. Bigger changes I get Davis to review. No semantic changes without discussion in issues

Changes

• Non S7 classes
  • as_class() centralises all handling of classes (base types, S3, S4, and S7)
  • Strings now only refer to base types (previously used for S3 + S7 class in parent frame) new_class( parent = "function")
  • Numeric, atomic, and vector "types" as S7 unions.
    • Should we provide some wrappers to base unions and consider if we could get rid of string representation altogether? (e.g. base_atomic)
  • New s3_class() to define S3 classes.
    • https://github.com/RConsortium/S7/pull/148 makes it possible for S7 class to extend an S3 class
    • Should we export the S3 class definitions for common base S3 classes? And then provide with base_factor etc.
  • S4 unions converted to S7 unions
• Method registration
  • Clarify difference between registration and dispatch. Will flow into refactoring of C code in near future.
  • Dispatch is base/S3/S4/S7 class with S7 generic.
  • Registration is base/S3/S4/S7 class with S7 generic AND S7 class with S3/S4 generic.
  • All combinations now tested.
  • Thorough refactoring of method registration
• Method dispatch
  • In generic, signature -> dispatch_args.
  • Simplified evaluation and restricted dispatch args (probably too much, but we relax as needed)
  • Should we provide a default dispatch argument name? x
• Validation
  • Validate types, then call validator()
  • Also call validator() for all super classes
  • New props<- for multi-assignment. Only validates at end.
• General QoL improvements to print() and str() methods

Next up

• Refactor method dispatch
• Defaults for properties, to get to point where constructor() without any argument usually works
• Dispatch on Missing/Any
• Coercion (cast())
• Eliminate next_method() (up_cast())
• Documentation

Discussion

• Speak about at rstudio::conf or useR?

  • Still need a real world application

  • Hadley to submit proposals to useR + rstudio::conf; and determine speakers and topics closer to the time

  • Next time we meet, we should discuss other ways to advertise

  • Ok to rename default branch from master to main? \~5 minutes work and unlikely to cause any problems.
  • Ok to eliminate prop_safely()? https://github.com/RConsortium/S7/issues/156
  • Convention for displaying class names: https://github.com/RConsortium/S7/issues/133 / https://github.com/RConsortium/S7/pull/161
  • Only show for S3/S4
  • Name of sentinel for missing/any dispatch: https://github.com/RConsortium/S7/issues/67
  • _arg looks good
  • Coercion: https://github.com/RConsortium/S7/issues/136

S7 documentation built on April 3, 2025, 10:50 p.m.