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RConsortium / S7 Public

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Support S7 extension of S4 classes and vice-versa#659

Merged

lawremi merged 79 commits into

mainRConsortium/S7:mainfrom

issue-456-s4-extends-s7RConsortium/S7:issue-456-s4-extends-s7Copy head branch name to clipboard

Jul 6, 2026

Conversation Commits79 (79)Checks Files changed

Merged

Support S7 extension of S4 classes and vice-versa#659
lawremi merged 79 commits into
mainfrom
issue-456-s4-extends-s7

Commits

Commits on Jun 27, 2026

use isClassUnion() instead of direct class check
lawremi
committed
pass className attribute directly to preserve package
lawremi
committed
since proper S4 classes can extend old classes, be stricter when reducing to an S3 class, and use methods::extends() to capture the entire class vector, not just the first class
lawremi
committed
fix is_oldClass() and use it in S4_to_S7_class()
lawremi
committed
initial implementation passing a simple test that does not depend on @() behavior, which needs to change in base R.
lawremi
committed
route S4 class registration through S4_register() and setOldClass(); S4_register() can now communicate any S7 class structure through the S4class= argument.
lawremi
committed
add a .lintr.R to allow for our symbol naming convention
lawremi
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S4-derived classes gain an initialize() method that mimics the default initialize() except uses the S7 property setting path.
lawremi
committed
call S4_register() automatically on S7 derivatives of S4 classes; fix parent object construction in constructor.
lawremi
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add some detailed notes on S4 compatibility to docs
lawremi
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fix S7 inheritance checks after rebase
lawremi
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drop the S7_object case from S4_register
lawremi
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docs: recommend use of initialize() when working with S7 derivatives of S4
lawremi
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clean up inheritance logic changes
lawremi
committed
just remove classes that exist instead of using try()
lawremi
committed
update the global variables for our use of @, which still confuses codetools
lawremi
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clean up constructor generation
lawremi
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fix test guarding against extension of S4 classes
lawremi
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allow abstract classes to inhert from virtual S4 classes
lawremi
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clean up S4 subclass setOldClass() registration; now supports more complex hierarchies
lawremi
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more tweaks to subclass registration
lawremi
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make S7_class_name robust to invocation at package build time
lawremi
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reformat
lawremi
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convert() falls back to methods::as()
lawremi
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correct S4 class name for 'to'
lawremi
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add test
lawremi
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convert_up() can convert an S4-derived S7 object to an S4 object
lawremi
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clean up and test restricted methods::as() fallback to convert()
lawremi
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S4_register() returns the name of the class it registered, which can be convenient for passing to methods package functions
lawremi
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rename S4_transient_prototype_class to S4_register_prototype_class and have it return the class name.
lawremi
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support class unions in S4_register()
lawremi
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make S4_class() return a methods-friendly class name and have it handle unions, particularly class_numeric
lawremi
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support S4 classes extending S7 classes
lawremi
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move away from do.call(setClass, ...); package is not needed on the prototype class
lawremi
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revert unnecessary direct attr() access
lawremi
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move a couple more S4 helpers from methods-register.R to S4.R
lawremi
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S7 classes inherit S4 class unions from S4 parents directly, which simplifies the S4 -> S7 -> S4 inheritance case.
lawremi
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avoid inherited slot conflicts in the S4->S7->S4 inheritance pattern
lawremi
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instead of forwarding S4 class unions into S7 classes, we enable S4_union_class() to find existing S4 unions.
lawremi
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update test snapshot after rebase
lawremi
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represent inheritance from S7_object at the S4 level
lawremi
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since @<- will dispatch to S7 setting even on S4 objects (derived from S7), we need to use R_do_slot_assign so that a NULL value does not delete the S4 slot.
lawremi
committed
inherits2() in prop.c handles S4 object case where class attribute is stored in the .S3Class slot.
lawremi
committed
tweaks to validObject hooks to support additional inheritance patterns
lawremi
committed
in obj_type(), isS4() takes precedence over has_S4_class(), since an S4 object is just that, even if it inherits from an S7 class and thus carries an S7_class slot.
lawremi
committed
restore method-register-S4.R; got lost in the rebase shuffle
lawremi
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prop storage now uses the S4 sentinel for NULL for low-level compatibility with S4; arguably a generally better approach since it avoids adding and deleting attributes based on whether the value is…
lawremi
committed
push S4 validation guard down into validate() so that it works for validate() as well as validObject()
lawremi
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Define S4 prototype on the ::S4Slots old class based on property defaults. We evaluate these if they are language objects, so S7 classes extending or being extended by S4 classes need to ensure tha…
lawremi
committed
mark the subclass old class as virtual, because there should never be an S4 instance of that class (old classes are virtual normally but not in this case since we pass an S4Class prototype)
lawremi
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give convert_up() a general as()-based fallback like convert()
lawremi
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make the ::S4Slots class non-virtual to enable more convenient construction
lawremi
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drop the up cast coercions (dead end) and instead ensure full slot representation along the old class chain
lawremi
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S3 method registration will also register an S4 method when the generic is internal and an element of the signature has an S4 ancestor. This is needed because internal generics will favor S4 method…
lawremi
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abstract S7 classes deriving from S4 classes are represented as ordinary S4 classes instead of old classes, because an old class implies an S3 instance of the object can exist, ie, there can be an …
lawremi
committed
old classes were missing S7_class as a declared slot, which can cause it to get stripped during S4 upcasting, breaking the S7 object
lawremi
committed
shorten the S4 registration helper name
lawremi
committed
allow multi-argument signature on internal generics via S4 generic definition
lawremi
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S4_initialize sets slots that aren't properties using slot<-, not prop<-
lawremi
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@<- supports setting slots on S4 objects
lawremi
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S4_validate_shim() does not try to validate objects from a "cousin" S7 class
lawremi
committed
adapt validObject() call to S7 validate contract
lawremi
committed
eliminate S7_object::S4Slots from hierarchy to simplify inheritance; in principle, there should only be one ::S4Slots shim for each S4 derivative of an S7 class
lawremi
committed
doc updates
lawremi
committed
wording tweak

lawremi
and
hadley
committed
Another wording tweak

lawremi
and
hadley
committed
rename is_multi_arg_signature to is_plain_list to clarify its (more general) purpose
lawremi
committed
clarify S4_register() by moving early returns earlier
lawremi
committed
move S4 inheritance guidance to the compatbility vignette
lawremi
committed
massive simplification: no longer define ::S4Slots variant to enable S4 to inherit from S7; there's just two types of classes: the stub old class and the reified old class. The former for when only…
lawremi
committed
add NEWS entry
lawremi
committed
post-rebase cleanup
lawremi
committed
revert accidental reversion of switch to := syntax
lawremi
committed
tighten up a test
lawremi
committed
fix local_S4_class(where=); bug was exposed by our stricter version of S4_remove_classes().
lawremi
committed
API rework: S4_register() always includes properties as slots (what contains=TRUE used to do), which ensures that classes are always able to be used as S4 superclasses. Introduce a separate helper …
lawremi
committed
fix regression from introduction of external generics
lawremi
committed
update for rename of @S7_class to @_S7_class
lawremi
committed
fix a few style / rebase issues
lawremi
committed

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