## New features * The default object constructor returned by `new_class()` has been updated. It now accepts lazy (promise) property defaults and includes dynamic properties with a `setter` in the constructor. Additionally, all custom property setters are now consistently invoked by the default constructor. If you're using S7 in an R package, you'll need to re-document to ensure that your documentation matches the updated usage (#438, #445). * The call context of a dispatched method (as visible in `sys.calls()` and `traceback()`) no longer includes the inlined method and generic, resulting in more compact and readable tracebacks. The dispatched method call now contains only the method name, which serves as a hint for retrieving the method. For example: `method(my_generic, class_double)`(x=10, ...). (#486) * New `nameOfClass()` method exported for S7 base classes, to enable usage like `inherits("foo", S7::class_character)` (#432, #458) * Added support for more base/S3 classes (#434): `class_POSIXlt`, `class_POSIXt`, `class_formula`, `class_call`, `class_language`, and `class_name`. * S7 provides a new automatic backward compatibility mechanism to provide a version of `@` that works in R before version 4.3 (#326). ## Bug fixes and minor improvements * `new_class()` now automatically infers the package name when called from within an R package (#459). * Improved error message when custom validators return invalid values (#454, #457). * Fixed S3 methods registration across packages (#422). * `convert()` now provides a default method to transform a parent class instance into a subclass, enabling class construction from a prototype (#444). * A custom property `getter()` no longer infinitely recurses when accessing itself (reported in #403, fixed in #406). * `method()`generates an informative message with class `S7_error_method_not_found` when dispatch fails (#387). * `method<-()` can create multimethods that dispatch on `NULL`. * In `new_class()`, properties can either be named by naming the element of the list or by supplying the `name` argument to `new_property()` (#371). * The `Ops` generic now falls back to base Ops behaviour when one of the arguments is not an S7 object (#320). This means that you get the somewhat inconsistent base behaviour, but means that S7 doesn't introduce a new axis of inconsistency. * `prop()` (#395) and `prop<-`/`@<-` (#396) have been optimized and rewritten in C. * `super()` now works with Ops methods (#357). * `validate()` is now always called after a custom property setter was invoked (reported in #393, fixed in #396).

* Classes get a more informative print method (#346). * Correctly register S3 methods for S7 objects with a package (#333). * External methods are now registered using an attribute of the S3 methods table rather than an element of that environment. This prevents a warning being generated during the "code/documentation mismatches" check in `R CMD check` (#342). * `class_missing` and `class_any` can now be unioned with `|` (#337). * `new_object()` no longer accepts `NULL` as `.parent`. * `new_object()` now correctly runs the validator from abstract parent classes (#329). * `new_object()` works better when custom property setters modify other properties. * `new_property()` gains a `validator` argument that allows you to specify a per-property validator (#275). * `new_property()` clarifies that it's the user's responsibility to return the correct class; it is _not_ automatically validated. * Properties with a custom setter are now validated _after_ the setter has run and are validated when the object is constructed or when you call `validate()`, not just when you modify them after construction. * `S7_inherits()` now accepts `class = NULL` to test if an object is any sort of S7 object (#347).

## May-July 2023 * `new_external_generic()` is only needed when you want a soft dependency on another package. * `methods_register()` now also registers S3 and S4 methods (#306). ## Jan-May 2023 * Subclasses of abstract class can have readonly properties (#269). * During construction, validation is now only performed once for each element of the class hierarchy (#248). * Implemented a better filtering strategy for the S4 class hierarchy so you can now correctly dispatch on virtual classes (#252). * New `set_props()` to make a modified copy of an object (#229). * `R CMD check` now passes on R 3.5 and greater (for tidyverse compatibility). * Dispatching on an evaluated argument no longer causes a crash (#254). * Improve method dispatch failure message (#231). * Can use `|` to create unions from S7 classes (#224). * Can no longer subclass an environment via `class_environment` because we need to think the consequences of this behaviour through more fully (#253). ## Rest of 2022 * Add `[.S7_object`, `[<-.S7_object`, `[[.S7_object`, and `[[<-.S7_object` methods to avoid "object of type 'S4' is not subsettable" error (@jamieRowen, #236). * Combining S7 classes with `c()` now gives an error (#230) * Base classes now show as `class_x` instead of `"x"` in method print (#232) ## Mar 2022 * Exported `class_factor`, `class_Date`, `class_POSIXct`, and `class_data.frame`. * New `S7_inherits()` and `check_is_S7()` (#193) * `new_class()` can create abstract classes (#199). * `method_call()` is now `S7_dispatch()` (#200). * Can now register methods for double-dispatch base Ops (currently only works if both classes are S7, or the first argument is S7 and the second doesn't have a method for the Ops generic) (#128). * All built-in wrappers around base types use `class_`. You can no longer refer to a base type with a string or a constructor function (#170). * `convert()` allows you to convert an object into another class (#136). * `super()` replaces `next_method()` (#110). ## Feb 2022 * `class_any` and `class_missing` make it possible to dispatch on absent arguments and arguments of any class (#67). * New `method_explain()` to explain dispatch (#194). * Minor property improvements: use same syntax for naming short-hand and full property specifications; input type automatically validated for custom setters. A property with a getter but no setter is read-only (#168). * When creating an object, unspecified properties are initialized with their default value (#67). DISCUSS: to achieve this, the constructor arguments default to `class_missing`. * Add `$.S7_object` and `$<-.S7_object` methods to avoid "object of type 'S4' is not subsettable" error (#204). * Dispatch now disambiguates between S4 and S3/S7, and, optionally, between S7 classes in different packages (#48, #163). * `new_generic()` now requires `dispatch_args` (#180). This means that `new_generic()` will typically be called without names. Either `new_generic("foo", "x")` for a "standard" generic, or `new_generic("foo", "x", function(x, y) call_method())` for a non-standard method. * `new_external_generic()` now requires `dispatch_args` so we can eagerly check the signature. * Revamp website. README now shows brief example and more info in `vignette("S7")`. Initial design docs and minutes are now articles so they appear on the website. ## Jan 2022 * New `props<-` for setting multiple properties simultaneously and validating afterwards (#149). * Validation now happens recursively, and validates types before validating the object (#149) * Classes (base types, S3, S4, and S7) are handled consistently wherever they are used. Strings now only refer to base types. New explicit `new_S3_class()` for referring to S3 classes (#134). S4 unions are converted to S7 unions (#150). * Base numeric, atomic, and vector "types" are now represented as class unions (#147). * Different evaluation mechanism for method dispatch, and greater restrictions on dispatch args (#141) * `x@.data` -> `S7_data()`; probably to be replaced by casting. * In generic, `signature` -> `dispatch_args`. * Polished `str()` and `print()` methods * `new_class()` has properties as 3rd argument (instead of constructor).