R6 2.5.1

R6 2.5.0

Resolved #195: Slightly clearer message when there is an error in the initialize() method.
Fixed #214: When a non-portable object inheritance was cloned, methods that were inherited (and not overridden) had the wrong environment. (#215, #217)
Printing R6 objects, no longer includes .__active__.

Cloning active bindings previously relied on buggy behavior in as.list.environment(), which would return the active binding’s function definition rather than the value from invoking the function. In R 4.0, the behavior will chang so that it returns the value. R6 now no longer relies on this buggy behavior. (#192)

Vignettes are no longer included as part of the source package because of their large size. Documentation is now at https://r6.r-lib.org/.
Fixed #125: The print.R6 method now always returns the object that was passed to it.
Fixed #155: In some cases, a cloned object’s methods could refer to the wrong super object. (#156)
Fixed #94, #133: When cloning an object which contained a function that is not a method, the corresponding function in the new object would have its environment changed, as though it were a method. Now it no longer has a changed environment. (#156)
Fixed #121: If a finalize method was present, it would prevent objects passed to initialize from getting GC’d.
Fixed #158: If a $set method of an R6 generator object is given the value NULL, it previously removed the named item. Now it adds the named item with the value NULL.
Fixed #159: Printing an R6 object containing a large vector was slow.

Fixed #108: When an object with a super object and an active binding in the super object was cloned, the new object’s super object did not get the active binding – it was a normal function.
Fixed #119: When a class had two levels of inheritance, an instance of that class’s super object could contain methods that had an incorrect enclosing environment.

Vignettes now only try use the microbenchmark package if it is present. This is so that the package builds properly on platforms where microbenchmark is not present, like Solaris.
Fixed ending position for trim().

Classes can define finalizers explicitly, by defining a public finalize method. (#92, #93)
Added function is.R6() and is.R6Class(). (#95)
Fixed #96: R6 now avoids using $ and [[ after the class has been assigned to the object. This allows the user to provide their own methods for $ and [[ without causing problems to R6’s operation.

The plot S3 method for R6 objects will call $plot on the object if present. (#77)
Fixed printing of members that are R6 objects. (#88)
Fixed deep cloning for non-portable classes. (#85)
Added as.list.R6 method. (#91)

Implemented format.R6() and format.R6ClassGenerator, the former calls a public format method if defined. This might change the functionality of existing classes that define a public format method intended for other purposes (#73. Thanks to Kirill Müller)
Functions are shown with their interface in print and format, limited to one line (#76. Thanks to Kirill Müller)
R6 objects and generators print out which class they inherit from. (#67)

Fixed a bug with printing R6 objects when a [[ method is defined for the class. (#70)
Fixed cloning of objects that call a super method which accesses private. (#72)

Added support for making clones of R6 objects with a clone() method on R6 objects. The deep=TRUE option allows for making clones that have copies of fields with reference semantics (like other R6 objects). (#27)
Allow adding public or private members when there were no public or private members to begin with. (#51)
Previously, when an R6 object was printed, it accessed (and called) active bindings. Now it simply reports that a field is an active binding. (#37, #38. Thanks to Oscar de Lama)
Printing private members now works correctly for portable R6 objects. (#26)
The ‘lock’ argument has been renamed to ‘lock_objects’. Also, there is a new argument, ‘lock_class’, which can prevent changes to the class. (#52)
Fixed printing of NULL fields.

[BREAKING CHANGE] Added portable option, which allows inheritance across different package namespaces, and made it the default.
Added set() method on class generator object, so new fields and methods can be added after the generator has been created.
All of the functions involved in instantiating objects are encapsulated in an environment separate from the R6 namespace. This means that if a generator is created with one version of R6, saved, then restored in a new R session that has a different version of R6, there shouldn’t be any problems with compatibility.
Methods are locked so that they can’t be changed. (Fixes #19)
Inheritance of superclasses is dynamic; instead of reading in the superclass when a class is created, this happens each time an object is instantiated. (Fixes #12)
Added trailing newline when printing R6 objects. (Thanks to Gabor Csardi)
The print method of R6 objects can be redefined. (Thanks to Gabor Csardi)