From 294e57caccd4c37d993dc2e9509e0614df89db98 Mon Sep 17 00:00:00 2001
From: Hadley Wickham <h.wickham@gmail.com>
Date: Fri, 22 May 2026 14:55:42 -0500
Subject: [PATCH 1/9] Implement `S7_classes()` and `S7_generics()`

Fixes #335
---
 NAMESPACE                        |  2 ++
 NEWS.md                          |  1 +
 R/introspect.R                   | 36 ++++++++++++++++++++++++++++++++
 _pkgdown.yml                     |  5 ++++-
 man/S7_classes.Rd                | 31 +++++++++++++++++++++++++++
 tests/testthat/test-introspect.R | 29 +++++++++++++++++++++++++
 6 files changed, 103 insertions(+), 1 deletion(-)
 create mode 100644 R/introspect.R
 create mode 100644 man/S7_classes.Rd
 create mode 100644 tests/testthat/test-introspect.R

diff --git a/NAMESPACE b/NAMESPACE
index c0dfa06a..77542cc4 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -38,8 +38,10 @@ export("prop<-")
 export("props<-")
 export(S4_register)
 export(S7_class)
+export(S7_classes)
 export(S7_data)
 export(S7_dispatch)
+export(S7_generics)
 export(S7_inherits)
 export(S7_object)
 export(as_class)
diff --git a/NEWS.md b/NEWS.md
index 795ec1fd..de18ab09 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,6 @@
 # S7 (development version)
 
+* `S7_classes()` and `S7_generics()` list the S7 classes / generics defined in a given environment (default: the caller's environment); pass `asNamespace("pkg")` to inspect a specific package (#335).
 * `new_object()` no longer materialises ALTREP parent values (e.g. `seq_len()`), so constructing an S7 object that wraps a large compact integer sequence is now O(1) in memory instead of O(n) (@kschaubroeck, #607).
 * Internal changes to support R-devel (4.6) (#592, #593, #598, #600).
 * `S7_error_method_not_found` now has a correct class vector without a duplicate `"error"` entry (@jjjermiah, #604)
diff --git a/R/introspect.R b/R/introspect.R
new file mode 100644
index 00000000..ce1ee58c
--- /dev/null
+++ b/R/introspect.R
@@ -0,0 +1,36 @@
+#' List S7 classes and generics in an environment
+#'
+#' @description
+#' * `S7_classes()` returns the names of S7 classes defined in `env`.
+#' * `S7_generics()` returns the names of S7 generics defined in `env`.
+#'
+#' @param env An environment. Defaults to the caller's environment.
+#'   To inspect a package, pass `asNamespace("pkg")`; to inspect the global
+#'   environment, pass `globalenv()`.
+#' @returns A character vector of names.
+#' @export
+#' @examples
+#' # List S7 classes exported by the S7 package itself
+#' S7_classes(asNamespace("S7"))
+#' S7_generics(asNamespace("S7"))
+S7_classes <- function(env = parent.frame()) {
+  find_objects(env, is_class)
+}
+
+#' @export
+#' @rdname S7_classes
+S7_generics <- function(env = parent.frame()) {
+  find_objects(env, is_S7_generic)
+}
+
+find_objects <- function(env, predicate) {
+  if (isNamespace(env)) {
+    # Not attached; use exported values
+    names <- getNamespaceExports(env)
+  } else {
+    # Attached or global; use all values
+    names <- ls(envir = env)
+  }
+
+  Filter(\(name) predicate(get(name, envir = env, inherits = FALSE)), names)
+}
diff --git a/_pkgdown.yml b/_pkgdown.yml
index 43bce828..b711c472 100644
--- a/_pkgdown.yml
+++ b/_pkgdown.yml
@@ -26,10 +26,13 @@ reference:
   - convert
   - class_missing
   - class_any
+  - super
+
+- title: Introspection
   - method
   - method_explain
-  - super
   - S7_class
+  - S7_classes
 
 - title: Packages
   desc: >
diff --git a/man/S7_classes.Rd b/man/S7_classes.Rd
new file mode 100644
index 00000000..f8ce8729
--- /dev/null
+++ b/man/S7_classes.Rd
@@ -0,0 +1,31 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/introspect.R
+\name{S7_classes}
+\alias{S7_classes}
+\alias{S7_generics}
+\title{List S7 classes and generics in an environment}
+\usage{
+S7_classes(env = parent.frame())
+
+S7_generics(env = parent.frame())
+}
+\arguments{
+\item{env}{An environment. Defaults to the caller's environment.}
+}
+\value{
+A character vector of names.
+}
+\description{
+\itemize{
+\item \code{S7_classes()} returns the names of S7 classes defined in \code{env}.
+\item \code{S7_generics()} returns the names of S7 generics defined in \code{env}.
+}
+
+To inspect a package, pass \code{asNamespace("pkg")}; to inspect the global
+environment, pass \code{globalenv()}.
+}
+\examples{
+# List S7 classes exported by the S7 package itself
+S7_classes(asNamespace("S7"))
+S7_generics(asNamespace("S7"))
+}
diff --git a/tests/testthat/test-introspect.R b/tests/testthat/test-introspect.R
new file mode 100644
index 00000000..9a3a244b
--- /dev/null
+++ b/tests/testthat/test-introspect.R
@@ -0,0 +1,29 @@
+test_that("S7_classes() / S7_generics() inspect a single environment", {
+  # Namespace: restricted to exports
+  expect_equal(S7_classes(asNamespace("S7")), "S7_object")
+  expect_equal(S7_generics(asNamespace("S7")), "convert")
+})
+
+test_that("default `env` is the caller's environment", {
+  local({
+    Foo <- new_class("Foo", package = NULL)
+    Bar <- new_class("Bar", package = NULL)
+    my_gen <- new_generic("my_gen", "x")
+
+    expect_setequal(S7_classes(), c("Foo", "Bar"))
+    expect_setequal(S7_generics(), "my_gen")
+  })
+
+  expect_setequal(S7_classes(), character())
+  expect_setequal(S7_generics(), character())
+})
+
+test_that("find_objects() returns matching names", {
+  env <- new.env(parent = emptyenv())
+  env$Foo <- new_class("Foo", package = NULL)
+  env$bar <- 1L
+  env$Baz <- new_class("Baz", package = NULL)
+
+  expect_setequal(find_objects(env, is_class), c("Foo", "Baz"))
+  expect_setequal(find_objects(env, is.integer), "bar")
+})

From cb67829c6dc3a5f0d0eceeb963020e85a8189ad8 Mon Sep 17 00:00:00 2001
From: Hadley Wickham <h.wickham@gmail.com>
Date: Fri, 22 May 2026 15:34:45 -0500
Subject: [PATCH 2/9] Draft `S7_methods()`

---
 NAMESPACE                           |  1 +
 NEWS.md                             |  2 +-
 R/introspect.R                      | 97 +++++++++++++++++++++++++++++
 _pkgdown.yml                        |  1 +
 man/S7_classes.Rd                   |  7 +--
 man/S7_methods.Rd                   | 39 ++++++++++++
 tests/testthat/_snaps/introspect.md | 18 ++++++
 tests/testthat/test-introspect.R    | 73 ++++++++++++++++++++++
 8 files changed, 233 insertions(+), 5 deletions(-)
 create mode 100644 man/S7_methods.Rd
 create mode 100644 tests/testthat/_snaps/introspect.md

diff --git a/NAMESPACE b/NAMESPACE
index 77542cc4..b2e2c17c 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -43,6 +43,7 @@ export(S7_data)
 export(S7_dispatch)
 export(S7_generics)
 export(S7_inherits)
+export(S7_methods)
 export(S7_object)
 export(as_class)
 export(check_is_S7)
diff --git a/NEWS.md b/NEWS.md
index de18ab09..9c2b67a7 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,6 +1,6 @@
 # S7 (development version)
 
-* `S7_classes()` and `S7_generics()` list the S7 classes / generics defined in a given environment (default: the caller's environment); pass `asNamespace("pkg")` to inspect a specific package (#335).
+* `S7_classes()`, `S7_generics()`, and `S7_methods()` are new introspection helpers. `S7_classes()` and `S7_generics()` list the S7 classes / generics defined in a given environment; pass `asNamespace("pkg")` to inspect a specific package. `S7_methods()` returns a data frame of methods registered on a generic, or registered for a class across all attached packages (#335).
 * `new_object()` no longer materialises ALTREP parent values (e.g. `seq_len()`), so constructing an S7 object that wraps a large compact integer sequence is now O(1) in memory instead of O(n) (@kschaubroeck, #607).
 * Internal changes to support R-devel (4.6) (#592, #593, #598, #600).
 * `S7_error_method_not_found` now has a correct class vector without a duplicate `"error"` entry (@jjjermiah, #604)
diff --git a/R/introspect.R b/R/introspect.R
index ce1ee58c..28b7edf1 100644
--- a/R/introspect.R
+++ b/R/introspect.R
@@ -23,6 +23,103 @@ S7_generics <- function(env = parent.frame()) {
   find_objects(env, is_S7_generic)
 }
 
+#' List S7 methods
+#'
+#' List the methods registered on an S7 `generic`, or the methods registered
+#' for a given `class` across all S7 generics defined in attached packages.
+#'
+#' @param generic An S7 generic. Mutually exclusive with `class`.
+#' @param class A class specification (anything accepted by [as_class()]).
+#'   When supplied, every S7 generic in every attached package is searched
+#'   for methods with this class in their signature. Mutually exclusive with
+#'   `generic`.
+#' @returns A data frame with one row per matching method and columns:
+#'
+#'   * `generic`: the generic's name.
+#'   * `signature`: human-readable description of the dispatch signature.
+#'   * `method`: a string giving the `method()` call that retrieves the
+#'     method.
+#' @export
+#' @examples
+#' Foo <- new_class("Foo", package = NULL)
+#' Bar <- new_class("Bar", package = NULL)
+#' my_gen <- new_generic("my_gen", "x")
+#' method(my_gen, Foo) <- function(x) "foo"
+#' method(my_gen, Bar) <- function(x) "bar"
+#'
+#' S7_methods(generic = my_gen)
+#' S7_methods(class = Foo)
+S7_methods <- function(generic = NULL, class = NULL) {
+  if (is.null(generic) == is.null(class)) {
+    stop("Must supply exactly one of `generic` or `class`.")
+  }
+
+  if (!is.null(generic)) {
+    if (!is_S7_generic(generic)) {
+      stop("`generic` must be an S7 generic.")
+    }
+    generics <- list(generic)
+    target <- NULL
+  } else {
+    target <- class_register(as_class(class))
+    generics <- attached_generics()
+  }
+
+  rows <- lapply(generics, function(g) generic_method_rows(g, target))
+  do.call(rbind, rows)
+}
+
+# Per-generic helper: turn the generic's registered methods into a data
+# frame, optionally filtering to those whose signature contains `target`.
+generic_method_rows <- function(generic, target = NULL) {
+  ms <- methods(generic)
+  if (length(ms) == 0) {
+    return(empty_methods_df())
+  }
+  if (!is.null(target)) {
+    keep <- vlapply(ms, \(m) {
+      any(vcapply(m@signature, class_register) == target)
+    })
+    ms <- ms[keep]
+  }
+  if (length(ms) == 0) {
+    return(empty_methods_df())
+  }
+
+  data.frame(
+    generic = rep(generic@name, length(ms)),
+    signature = vcapply(
+      ms,
+      \(m) paste0(vcapply(m@signature, class_desc), collapse = ", ")
+    ),
+    method = vcapply(ms, \(m) method_signature(generic, m@signature))
+  )
+}
+
+empty_methods_df <- function() {
+  data.frame(
+    generic = character(),
+    signature = character(),
+    method = character()
+  )
+}
+
+# All S7 generics reachable from attached packages and the global env.
+attached_generics <- function() {
+  envs <- attached_envs()
+  out <- list()
+  for (env in envs) {
+    for (name in S7_generics(env)) {
+      out[[length(out) + 1L]] <- get0(name, envir = env, inherits = FALSE)
+    }
+  }
+  out
+}
+
+attached_envs <- function() {
+  lapply(search(), as.environment)
+}
+
 find_objects <- function(env, predicate) {
   if (isNamespace(env)) {
     # Not attached; use exported values
diff --git a/_pkgdown.yml b/_pkgdown.yml
index b711c472..cd7970d4 100644
--- a/_pkgdown.yml
+++ b/_pkgdown.yml
@@ -33,6 +33,7 @@ reference:
   - method_explain
   - S7_class
   - S7_classes
+  - S7_methods
 
 - title: Packages
   desc: >
diff --git a/man/S7_classes.Rd b/man/S7_classes.Rd
index f8ce8729..5f9d1dd7 100644
--- a/man/S7_classes.Rd
+++ b/man/S7_classes.Rd
@@ -10,7 +10,9 @@ S7_classes(env = parent.frame())
 S7_generics(env = parent.frame())
 }
 \arguments{
-\item{env}{An environment. Defaults to the caller's environment.}
+\item{env}{An environment. Defaults to the caller's environment.
+To inspect a package, pass \code{asNamespace("pkg")}; to inspect the global
+environment, pass \code{globalenv()}.}
 }
 \value{
 A character vector of names.
@@ -20,9 +22,6 @@ A character vector of names.
 \item \code{S7_classes()} returns the names of S7 classes defined in \code{env}.
 \item \code{S7_generics()} returns the names of S7 generics defined in \code{env}.
 }
-
-To inspect a package, pass \code{asNamespace("pkg")}; to inspect the global
-environment, pass \code{globalenv()}.
 }
 \examples{
 # List S7 classes exported by the S7 package itself
diff --git a/man/S7_methods.Rd b/man/S7_methods.Rd
new file mode 100644
index 00000000..a034c429
--- /dev/null
+++ b/man/S7_methods.Rd
@@ -0,0 +1,39 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/introspect.R
+\name{S7_methods}
+\alias{S7_methods}
+\title{List S7 methods}
+\usage{
+S7_methods(generic = NULL, class = NULL)
+}
+\arguments{
+\item{generic}{An S7 generic. Mutually exclusive with \code{class}.}
+
+\item{class}{A class specification (anything accepted by \code{\link[=as_class]{as_class()}}).
+When supplied, every S7 generic in every attached package is searched
+for methods with this class in their signature. Mutually exclusive with
+\code{generic}.}
+}
+\value{
+A data frame with one row per matching method and columns:
+\itemize{
+\item \code{generic}: the generic's name.
+\item \code{signature}: human-readable description of the dispatch signature.
+\item \code{method}: a string giving the \code{method()} call that retrieves the
+method.
+}
+}
+\description{
+List the methods registered on an S7 \code{generic}, or the methods registered
+for a given \code{class} across all S7 generics defined in attached packages.
+}
+\examples{
+Foo <- new_class("Foo", package = NULL)
+Bar <- new_class("Bar", package = NULL)
+my_gen <- new_generic("my_gen", "x")
+method(my_gen, Foo) <- function(x) "foo"
+method(my_gen, Bar) <- function(x) "bar"
+
+S7_methods(generic = my_gen)
+S7_methods(class = Foo)
+}
diff --git a/tests/testthat/_snaps/introspect.md b/tests/testthat/_snaps/introspect.md
new file mode 100644
index 00000000..2db68411
--- /dev/null
+++ b/tests/testthat/_snaps/introspect.md
@@ -0,0 +1,18 @@
+# S7_methods() validates inputs
+
+    Code
+      S7_methods()
+    Condition
+      Error in `S7_methods()`:
+      ! Must supply exactly one of `generic` or `class`.
+    Code
+      S7_methods(generic = new_generic("g", "x"), class = class_integer)
+    Condition
+      Error in `S7_methods()`:
+      ! Must supply exactly one of `generic` or `class`.
+    Code
+      S7_methods(generic = "not a generic")
+    Condition
+      Error in `S7_methods()`:
+      ! `generic` must be an S7 generic.
+
diff --git a/tests/testthat/test-introspect.R b/tests/testthat/test-introspect.R
index 9a3a244b..3444184c 100644
--- a/tests/testthat/test-introspect.R
+++ b/tests/testthat/test-introspect.R
@@ -18,6 +18,79 @@ test_that("default `env` is the caller's environment", {
   expect_setequal(S7_generics(), character())
 })
 
+test_that("S7_methods(generic) lists registered methods", {
+  Foo <- new_class("Foo", package = NULL)
+  Bar <- new_class("Bar", package = NULL)
+  gen <- new_generic("gen", "x")
+  method(gen, Foo) <- function(x) "foo"
+  method(gen, Bar) <- function(x) "bar"
+
+  res <- S7_methods(generic = gen)
+  expect_s3_class(res, "data.frame")
+  expect_named(res, c("generic", "signature", "method"))
+  expect_equal(res$generic, c("gen", "gen"))
+  expect_setequal(res$signature, c("<Foo>", "<Bar>"))
+  expect_setequal(res$method, c("method(gen, Foo)", "method(gen, Bar)"))
+})
+
+test_that("S7_methods(generic) handles multi-dispatch", {
+  Foo <- new_class("Foo", package = NULL)
+  Bar <- new_class("Bar", package = NULL)
+  gen <- new_generic("gen", c("x", "y"))
+  method(gen, list(Foo, Bar)) <- function(x, y) "fb"
+
+  res <- S7_methods(generic = gen)
+  expect_equal(res$signature, "<Foo>, <Bar>")
+  expect_equal(res$method, "method(gen, list(Foo, Bar))")
+})
+
+test_that("S7_methods(generic) returns empty df when no methods", {
+  gen <- new_generic("gen", "x")
+  res <- S7_methods(generic = gen)
+  expect_s3_class(res, "data.frame")
+  expect_equal(nrow(res), 0)
+  expect_named(res, c("generic", "signature", "method"))
+})
+
+test_that("S7_methods(class) scans attached generics", {
+  Foo <- new_class("Foo", package = NULL)
+  Bar <- new_class("Bar", package = NULL)
+  g1 <- new_generic("S7_introspect_g1_xyzzy", "x")
+  g2 <- new_generic("S7_introspect_g2_xyzzy", "x")
+  method(g1, Foo) <- function(x) "foo"
+  method(g2, Bar) <- function(x) "bar"
+
+  assign("S7_introspect_g1_xyzzy", g1, envir = globalenv())
+  assign("S7_introspect_g2_xyzzy", g2, envir = globalenv())
+  defer(rm(
+    list = c("S7_introspect_g1_xyzzy", "S7_introspect_g2_xyzzy"),
+    envir = globalenv()
+  ))
+
+  res <- S7_methods(class = Foo)
+  expect_true("S7_introspect_g1_xyzzy" %in% res$generic)
+  expect_false("S7_introspect_g2_xyzzy" %in% res$generic)
+})
+
+test_that("S7_methods() validates inputs", {
+  expect_snapshot(error = TRUE, {
+    S7_methods()
+    S7_methods(generic = new_generic("g", "x"), class = class_integer)
+    S7_methods(generic = "not a generic")
+  })
+})
+
+test_that("the `method` column round-trips via eval(parse(...))", {
+  Foo <- new_class("Foo", package = NULL)
+  gen <- new_generic("gen", "x")
+  method(gen, Foo) <- function(x) "foo result"
+
+  res <- S7_methods(generic = gen)
+  m <- eval(parse(text = res$method[1]))
+  expect_s3_class(m, "S7_method")
+  expect_equal(m(Foo()), "foo result")
+})
+
 test_that("find_objects() returns matching names", {
   env <- new.env(parent = emptyenv())
   env$Foo <- new_class("Foo", package = NULL)

From 46442f92153dd096d7bbc095ed16235ca3b34156 Mon Sep 17 00:00:00 2001
From: Hadley Wickham <h.wickham@gmail.com>
Date: Fri, 22 May 2026 15:35:51 -0500
Subject: [PATCH 3/9] News bullet

---
 NEWS.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/NEWS.md b/NEWS.md
index 9c2b67a7..d17d67cc 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,6 +1,6 @@
 # S7 (development version)
 
-* `S7_classes()`, `S7_generics()`, and `S7_methods()` are new introspection helpers. `S7_classes()` and `S7_generics()` list the S7 classes / generics defined in a given environment; pass `asNamespace("pkg")` to inspect a specific package. `S7_methods()` returns a data frame of methods registered on a generic, or registered for a class across all attached packages (#335).
+* `S7_classes()`, `S7_generics()`, and `S7_methods()` are new introspection helpers. `S7_classes()` and `S7_generics()` list the S7 classes / generics defined in a given environment; pass `asNamespace("pkg")` to inspect a specific package (#335). `S7_methods()` returns a data frame of methods registered on a generic, or — analogously to `utils::methods(class = )` — registered for a class across all attached packages (#435).
 * `new_object()` no longer materialises ALTREP parent values (e.g. `seq_len()`), so constructing an S7 object that wraps a large compact integer sequence is now O(1) in memory instead of O(n) (@kschaubroeck, #607).
 * Internal changes to support R-devel (4.6) (#592, #593, #598, #600).
 * `S7_error_method_not_found` now has a correct class vector without a duplicate `"error"` entry (@jjjermiah, #604)

From bcfc021c94a043ee52c36ce2c8081209c98ce15a Mon Sep 17 00:00:00 2001
From: Hadley Wickham <h.wickham@gmail.com>
Date: Mon, 1 Jun 2026 16:26:37 -0400
Subject: [PATCH 4/9] Restrict attached_envs

---
 R/introspect.R | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/R/introspect.R b/R/introspect.R
index 28b7edf1..eec9a494 100644
--- a/R/introspect.R
+++ b/R/introspect.R
@@ -117,7 +117,11 @@ attached_generics <- function() {
 }
 
 attached_envs <- function() {
-  lapply(search(), as.environment)
+  envs <- search()
+  pkgs <- envs[grepl("^package:", envs)]
+  pkgs <- setdiff(pkgs, "package:base")
+
+  c(lapply(pkgs, as.environment), globalenv())
 }
 
 find_objects <- function(env, predicate) {

From a56e2e8b632938ba08f2dd723a74e25396ab7c9a Mon Sep 17 00:00:00 2001
From: Hadley Wickham <h.wickham@gmail.com>
Date: Mon, 1 Jun 2026 16:37:46 -0400
Subject: [PATCH 5/9] Reduce some duplication

---
 R/introspect.R | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/R/introspect.R b/R/introspect.R
index eec9a494..e21b0e4a 100644
--- a/R/introspect.R
+++ b/R/introspect.R
@@ -106,12 +106,9 @@ empty_methods_df <- function() {
 
 # All S7 generics reachable from attached packages and the global env.
 attached_generics <- function() {
-  envs <- attached_envs()
   out <- list()
-  for (env in envs) {
-    for (name in S7_generics(env)) {
-      out[[length(out) + 1L]] <- get0(name, envir = env, inherits = FALSE)
-    }
+  for (env in attached_envs()) {
+    out <- c(out, unname(find_matches(env, is_S7_generic)))
   }
   out
 }
@@ -125,6 +122,11 @@ attached_envs <- function() {
 }
 
 find_objects <- function(env, predicate) {
+  names(find_matches(env, predicate))
+}
+
+# Named list of objects in `env` satisfying `predicate`.
+find_matches <- function(env, predicate) {
   if (isNamespace(env)) {
     # Not attached; use exported values
     names <- getNamespaceExports(env)
@@ -133,5 +135,6 @@ find_objects <- function(env, predicate) {
     names <- ls(envir = env)
   }
 
-  Filter(\(name) predicate(get(name, envir = env, inherits = FALSE)), names)
+  objs <- mget(names, envir = env, inherits = FALSE)
+  Filter(predicate, objs)
 }

From 7d22ebdb606f8a231c239279bf79c30f4fa22651 Mon Sep 17 00:00:00 2001
From: Hadley Wickham <h.wickham@gmail.com>
Date: Mon, 1 Jun 2026 16:39:36 -0400
Subject: [PATCH 6/9] Style

---
 R/introspect.R | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/R/introspect.R b/R/introspect.R
index e21b0e4a..95732809 100644
--- a/R/introspect.R
+++ b/R/introspect.R
@@ -88,10 +88,9 @@ generic_method_rows <- function(generic, target = NULL) {
 
   data.frame(
     generic = rep(generic@name, length(ms)),
-    signature = vcapply(
-      ms,
-      \(m) paste0(vcapply(m@signature, class_desc), collapse = ", ")
-    ),
+    signature = vcapply(ms, function(m) {
+      paste0(vcapply(m@signature, class_desc), collapse = ", ")
+    }),
     method = vcapply(ms, \(m) method_signature(generic, m@signature))
   )
 }

From 39ba25d503d74a9dca79f0fe1ee83bd746904033 Mon Sep 17 00:00:00 2001
From: Hadley Wickham <h.wickham@gmail.com>
Date: Tue, 2 Jun 2026 11:36:31 -0400
Subject: [PATCH 7/9] More polishing

---
 R/introspect.R                      | 68 ++++++++++++++++-------------
 _pkgdown.yml                        |  2 +-
 man/S7_classes.Rd                   |  2 +-
 man/S7_methods.Rd                   |  8 ++--
 tests/testthat/_snaps/introspect.md | 10 -----
 tests/testthat/test-introspect.R    | 19 ++++++--
 6 files changed, 59 insertions(+), 50 deletions(-)

diff --git a/R/introspect.R b/R/introspect.R
index 95732809..fa0d3ee4 100644
--- a/R/introspect.R
+++ b/R/introspect.R
@@ -1,4 +1,4 @@
-#' List S7 classes and generics in an environment
+#' Find S7 classes and generics in an environment
 #'
 #' @description
 #' * `S7_classes()` returns the names of S7 classes defined in `env`.
@@ -28,14 +28,16 @@ S7_generics <- function(env = parent.frame()) {
 #' List the methods registered on an S7 `generic`, or the methods registered
 #' for a given `class` across all S7 generics defined in attached packages.
 #'
-#' @param generic An S7 generic. Mutually exclusive with `class`.
+#' @param generic An S7 generic.
 #' @param class A class specification (anything accepted by [as_class()]).
 #'   When supplied, every S7 generic in every attached package is searched
-#'   for methods with this class in their signature. Mutually exclusive with
-#'   `generic`.
+#'   for methods with this class in their signature.
 #' @returns A data frame with one row per matching method and columns:
 #'
 #'   * `generic`: the generic's name.
+#'   * `package`: the package the generic is defined in, or `NA` for generics
+#'     found in the global environment (or when `generic` is supplied
+#'     directly).
 #'   * `signature`: human-readable description of the dispatch signature.
 #'   * `method`: a string giving the `method()` call that retrieves the
 #'     method.
@@ -50,44 +52,44 @@ S7_generics <- function(env = parent.frame()) {
 #' S7_methods(generic = my_gen)
 #' S7_methods(class = Foo)
 S7_methods <- function(generic = NULL, class = NULL) {
-  if (is.null(generic) == is.null(class)) {
-    stop("Must supply exactly one of `generic` or `class`.")
-  }
-
   if (!is.null(generic)) {
     if (!is_S7_generic(generic)) {
       stop("`generic` must be an S7 generic.")
     }
-    generics <- list(generic)
-    target <- NULL
+    generics <- list(list(generic = generic, package = NA_character_))
   } else {
-    target <- class_register(as_class(class))
     generics <- attached_generics()
   }
 
-  rows <- lapply(generics, function(g) generic_method_rows(g, target))
+  if (!is.null(class)) {
+    target <- class_register(as_class(class))
+  } else {
+    target <- NULL
+  }
+
+  rows <- lapply(generics, function(g) {
+    generic_method_rows(g$generic, g$package, target)
+  })
   do.call(rbind, rows)
 }
 
 # Per-generic helper: turn the generic's registered methods into a data
 # frame, optionally filtering to those whose signature contains `target`.
-generic_method_rows <- function(generic, target = NULL) {
+generic_method_rows <- function(
+  generic,
+  package = NA_character_,
+  target = NULL
+) {
   ms <- methods(generic)
-  if (length(ms) == 0) {
-    return(empty_methods_df())
-  }
   if (!is.null(target)) {
-    keep <- vlapply(ms, \(m) {
+    ms <- Filter(x = ms, function(m) {
       any(vcapply(m@signature, class_register) == target)
     })
-    ms <- ms[keep]
-  }
-  if (length(ms) == 0) {
-    return(empty_methods_df())
   }
 
   data.frame(
     generic = rep(generic@name, length(ms)),
+    package = rep(package, length(ms)),
     signature = vcapply(ms, function(m) {
       paste0(vcapply(m@signature, class_desc), collapse = ", ")
     }),
@@ -95,23 +97,27 @@ generic_method_rows <- function(generic, target = NULL) {
   )
 }
 
-empty_methods_df <- function() {
-  data.frame(
-    generic = character(),
-    signature = character(),
-    method = character()
-  )
-}
-
-# All S7 generics reachable from attached packages and the global env.
+# All S7 generics reachable from attached packages and the global env,
+# each tagged with the package it was found in (`NA` for the global env).
 attached_generics <- function() {
   out <- list()
   for (env in attached_envs()) {
-    out <- c(out, unname(find_matches(env, is_S7_generic)))
+    package <- env_package(env)
+    for (generic in unname(find_matches(env, is_S7_generic))) {
+      out[[length(out) + 1L]] <- list(generic = generic, package = package)
+    }
   }
   out
 }
 
+env_package <- function(env) {
+  if (identical(env, globalenv())) {
+    NA_character_
+  } else {
+    sub("^package:", "", environmentName(env))
+  }
+}
+
 attached_envs <- function() {
   envs <- search()
   pkgs <- envs[grepl("^package:", envs)]
diff --git a/_pkgdown.yml b/_pkgdown.yml
index ea0af336..cd3c38fd 100644
--- a/_pkgdown.yml
+++ b/_pkgdown.yml
@@ -33,9 +33,9 @@ reference:
   - method
   - method_explain
   - S7_class
+  - S7_class_desc
   - S7_classes
   - S7_methods
-  - S7_class_desc
 
 - title: Packages
   desc: >
diff --git a/man/S7_classes.Rd b/man/S7_classes.Rd
index 5f9d1dd7..facfb7fc 100644
--- a/man/S7_classes.Rd
+++ b/man/S7_classes.Rd
@@ -3,7 +3,7 @@
 \name{S7_classes}
 \alias{S7_classes}
 \alias{S7_generics}
-\title{List S7 classes and generics in an environment}
+\title{Find S7 classes and generics in an environment}
 \usage{
 S7_classes(env = parent.frame())
 
diff --git a/man/S7_methods.Rd b/man/S7_methods.Rd
index a034c429..2c2ce6d5 100644
--- a/man/S7_methods.Rd
+++ b/man/S7_methods.Rd
@@ -7,17 +7,19 @@
 S7_methods(generic = NULL, class = NULL)
 }
 \arguments{
-\item{generic}{An S7 generic. Mutually exclusive with \code{class}.}
+\item{generic}{An S7 generic.}
 
 \item{class}{A class specification (anything accepted by \code{\link[=as_class]{as_class()}}).
 When supplied, every S7 generic in every attached package is searched
-for methods with this class in their signature. Mutually exclusive with
-\code{generic}.}
+for methods with this class in their signature.}
 }
 \value{
 A data frame with one row per matching method and columns:
 \itemize{
 \item \code{generic}: the generic's name.
+\item \code{package}: the package the generic is defined in, or \code{NA} for generics
+found in the global environment (or when \code{generic} is supplied
+directly).
 \item \code{signature}: human-readable description of the dispatch signature.
 \item \code{method}: a string giving the \code{method()} call that retrieves the
 method.
diff --git a/tests/testthat/_snaps/introspect.md b/tests/testthat/_snaps/introspect.md
index 2db68411..9067ba9d 100644
--- a/tests/testthat/_snaps/introspect.md
+++ b/tests/testthat/_snaps/introspect.md
@@ -1,15 +1,5 @@
 # S7_methods() validates inputs
 
-    Code
-      S7_methods()
-    Condition
-      Error in `S7_methods()`:
-      ! Must supply exactly one of `generic` or `class`.
-    Code
-      S7_methods(generic = new_generic("g", "x"), class = class_integer)
-    Condition
-      Error in `S7_methods()`:
-      ! Must supply exactly one of `generic` or `class`.
     Code
       S7_methods(generic = "not a generic")
     Condition
diff --git a/tests/testthat/test-introspect.R b/tests/testthat/test-introspect.R
index 3444184c..901211bf 100644
--- a/tests/testthat/test-introspect.R
+++ b/tests/testthat/test-introspect.R
@@ -27,7 +27,7 @@ test_that("S7_methods(generic) lists registered methods", {
 
   res <- S7_methods(generic = gen)
   expect_s3_class(res, "data.frame")
-  expect_named(res, c("generic", "signature", "method"))
+  expect_named(res, c("generic", "package", "signature", "method"))
   expect_equal(res$generic, c("gen", "gen"))
   expect_setequal(res$signature, c("<Foo>", "<Bar>"))
   expect_setequal(res$method, c("method(gen, Foo)", "method(gen, Bar)"))
@@ -49,7 +49,7 @@ test_that("S7_methods(generic) returns empty df when no methods", {
   res <- S7_methods(generic = gen)
   expect_s3_class(res, "data.frame")
   expect_equal(nrow(res), 0)
-  expect_named(res, c("generic", "signature", "method"))
+  expect_named(res, c("generic", "package", "signature", "method"))
 })
 
 test_that("S7_methods(class) scans attached generics", {
@@ -70,12 +70,23 @@ test_that("S7_methods(class) scans attached generics", {
   res <- S7_methods(class = Foo)
   expect_true("S7_introspect_g1_xyzzy" %in% res$generic)
   expect_false("S7_introspect_g2_xyzzy" %in% res$generic)
+  expect_equal(
+    res$package[res$generic == "S7_introspect_g1_xyzzy"],
+    NA_character_
+  )
+})
+
+test_that("S7_methods() reports the generic's package", {
+  Foo <- new_class("Foo", package = NULL)
+  gen <- new_generic("gen", "x")
+  method(gen, Foo) <- function(x) "foo"
+
+  res <- S7_methods(generic = gen)
+  expect_equal(res$package, NA_character_)
 })
 
 test_that("S7_methods() validates inputs", {
   expect_snapshot(error = TRUE, {
-    S7_methods()
-    S7_methods(generic = new_generic("g", "x"), class = class_integer)
     S7_methods(generic = "not a generic")
   })
 })

From 10dc991eb7b167a6ffcf790657ed94e40534a357 Mon Sep 17 00:00:00 2001
From: Hadley Wickham <h.wickham@gmail.com>
Date: Wed, 3 Jun 2026 15:29:28 -0400
Subject: [PATCH 8/9] Tweak columns

---
 NAMESPACE                                |  4 ++
 R/introspect.R                           | 48 ++++++++++++++----------
 R/method-register.R                      | 11 ++++++
 man/S7_methods.Rd                        |  5 +--
 tests/testthat/_snaps/introspect.md      |  9 +++++
 tests/testthat/_snaps/method-register.md |  7 ++++
 tests/testthat/test-introspect.R         | 44 +++++++++++++---------
 tests/testthat/test-method-register.R    |  8 ++++
 8 files changed, 97 insertions(+), 39 deletions(-)

diff --git a/NAMESPACE b/NAMESPACE
index 080412ed..483678c9 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -11,6 +11,8 @@ S3method("|",S7_class)
 S3method(Ops,S7_object)
 S3method(Ops,S7_super)
 S3method(c,S7_class)
+S3method(format,S7_signature)
+S3method(format,S7_signature_list)
 S3method(print,S7_S3_class)
 S3method(print,S7_any)
 S3method(print,S7_base_class)
@@ -21,6 +23,8 @@ S3method(print,S7_method)
 S3method(print,S7_missing)
 S3method(print,S7_object)
 S3method(print,S7_property)
+S3method(print,S7_signature)
+S3method(print,S7_signature_list)
 S3method(print,S7_super)
 S3method(print,S7_union)
 S3method(str,S7_S3_class)
diff --git a/R/introspect.R b/R/introspect.R
index fa0d3ee4..243942a2 100644
--- a/R/introspect.R
+++ b/R/introspect.R
@@ -38,9 +38,8 @@ S7_generics <- function(env = parent.frame()) {
 #'   * `package`: the package the generic is defined in, or `NA` for generics
 #'     found in the global environment (or when `generic` is supplied
 #'     directly).
-#'   * `signature`: human-readable description of the dispatch signature.
-#'   * `method`: a string giving the `method()` call that retrieves the
-#'     method.
+#'   * `signature`: a list column of `S7_signature` objects describing the
+#'     dispatch signature. `format()` them for a human-readable description.
 #' @export
 #' @examples
 #' Foo <- new_class("Foo", package = NULL)
@@ -70,33 +69,44 @@ S7_methods <- function(generic = NULL, class = NULL) {
   rows <- lapply(generics, function(g) {
     generic_method_rows(g$generic, g$package, target)
   })
-  do.call(rbind, rows)
+  out <- do.call(rbind, rows)
+  out$signature <- new_signature_list(out$signature)
+  out
 }
 
-# Per-generic helper: turn the generic's registered methods into a data
-# frame, optionally filtering to those whose signature contains `target`.
-generic_method_rows <- function(
-  generic,
-  package = NA_character_,
-  target = NULL
-) {
+generic_method_rows <- function(generic, package, class) {
   ms <- methods(generic)
-  if (!is.null(target)) {
-    ms <- Filter(x = ms, function(m) {
-      any(vcapply(m@signature, class_register) == target)
-    })
+  if (!is.null(class)) {
+    has_class <- function(m) any(vcapply(m@signature, class_register) == class)
+    ms <- Filter(has_class, ms)
   }
 
   data.frame(
     generic = rep(generic@name, length(ms)),
     package = rep(package, length(ms)),
-    signature = vcapply(ms, function(m) {
-      paste0(vcapply(m@signature, class_desc), collapse = ", ")
-    }),
-    method = vcapply(ms, \(m) method_signature(generic, m@signature))
+    signature = I(lapply(ms, \(m) new_signature(m@signature)))
   )
 }
 
+# A list column of S7_signatures, used by S7_methods(). Needs its own class
+# so that print.data.frame() formats it per-element: data frames format whole
+# columns, so the scalar format.S7_signature() method is never reached.
+new_signature_list <- function(x) {
+  class(x) <- "S7_signature_list"
+  x
+}
+
+#' @export
+format.S7_signature_list <- function(x, ...) {
+  vcapply(unclass(x), format)
+}
+
+#' @export
+print.S7_signature_list <- function(x, ...) {
+  print(format(x), quote = FALSE)
+  invisible(x)
+}
+
 # All S7 generics reachable from attached packages and the global env,
 # each tagged with the package it was found in (`NA` for the global env).
 attached_generics <- function() {
diff --git a/R/method-register.R b/R/method-register.R
index 663013e2..b5a43729 100644
--- a/R/method-register.R
+++ b/R/method-register.R
@@ -290,6 +290,17 @@ new_signature <- function(x) {
   x
 }
 
+#' @export
+format.S7_signature <- function(x, ...) {
+  paste0(vcapply(unclass(x), class_desc), collapse = ", ")
+}
+
+#' @export
+print.S7_signature <- function(x, ...) {
+  cat(format(x), "\n", sep = "")
+  invisible(x)
+}
+
 check_method <- function(
   method,
   generic,
diff --git a/man/S7_methods.Rd b/man/S7_methods.Rd
index 2c2ce6d5..810b12b0 100644
--- a/man/S7_methods.Rd
+++ b/man/S7_methods.Rd
@@ -20,9 +20,8 @@ A data frame with one row per matching method and columns:
 \item \code{package}: the package the generic is defined in, or \code{NA} for generics
 found in the global environment (or when \code{generic} is supplied
 directly).
-\item \code{signature}: human-readable description of the dispatch signature.
-\item \code{method}: a string giving the \code{method()} call that retrieves the
-method.
+\item \code{signature}: a list column of \code{S7_signature} objects describing the
+dispatch signature. \code{format()} them for a human-readable description.
 }
 }
 \description{
diff --git a/tests/testthat/_snaps/introspect.md b/tests/testthat/_snaps/introspect.md
index 9067ba9d..40e3b9ad 100644
--- a/tests/testthat/_snaps/introspect.md
+++ b/tests/testthat/_snaps/introspect.md
@@ -1,3 +1,12 @@
+# S7_methods() prints the signature column readably
+
+    Code
+      print(S7_methods(generic = gen))
+    Output
+        generic package signature
+      1     gen    <NA>     <Foo>
+      2     gen    <NA>     <Bar>
+
 # S7_methods() validates inputs
 
     Code
diff --git a/tests/testthat/_snaps/method-register.md b/tests/testthat/_snaps/method-register.md
index 2648d432..39fee0c6 100644
--- a/tests/testthat/_snaps/method-register.md
+++ b/tests/testthat/_snaps/method-register.md
@@ -105,6 +105,13 @@
       Error:
       ! `signature` must be length 2.
 
+# S7_signature has format and print methods
+
+    Code
+      print(sig)
+    Output
+      <integer>, <character>
+
 # check_method complains if the functions are not compatible
 
     Code
diff --git a/tests/testthat/test-introspect.R b/tests/testthat/test-introspect.R
index 901211bf..d3f756d3 100644
--- a/tests/testthat/test-introspect.R
+++ b/tests/testthat/test-introspect.R
@@ -27,10 +27,32 @@ test_that("S7_methods(generic) lists registered methods", {
 
   res <- S7_methods(generic = gen)
   expect_s3_class(res, "data.frame")
-  expect_named(res, c("generic", "package", "signature", "method"))
+  expect_named(res, c("generic", "package", "signature"))
   expect_equal(res$generic, c("gen", "gen"))
-  expect_setequal(res$signature, c("<Foo>", "<Bar>"))
-  expect_setequal(res$method, c("method(gen, Foo)", "method(gen, Bar)"))
+  expect_setequal(vcapply(res$signature, format), c("<Foo>", "<Bar>"))
+})
+
+test_that("S7_methods() prints the signature column readably", {
+  Foo <- new_class("Foo", package = NULL)
+  Bar <- new_class("Bar", package = NULL)
+  gen <- new_generic("gen", "x")
+  method(gen, Foo) <- function(x) "foo"
+  method(gen, Bar) <- function(x) "bar"
+
+  expect_snapshot(print(S7_methods(generic = gen)))
+})
+
+test_that("S7_signature_list formats per element", {
+  foo <- new_generic("foo", c("x", "y"))
+  sigs <- new_signature_list(list(
+    as_signature(list(class_integer, class_character), foo),
+    as_signature(list(class_double, class_logical), foo)
+  ))
+
+  expect_equal(
+    format(sigs),
+    c("<integer>, <character>", "<double>, <logical>")
+  )
 })
 
 test_that("S7_methods(generic) handles multi-dispatch", {
@@ -40,8 +62,7 @@ test_that("S7_methods(generic) handles multi-dispatch", {
   method(gen, list(Foo, Bar)) <- function(x, y) "fb"
 
   res <- S7_methods(generic = gen)
-  expect_equal(res$signature, "<Foo>, <Bar>")
-  expect_equal(res$method, "method(gen, list(Foo, Bar))")
+  expect_equal(vcapply(res$signature, format), "<Foo>, <Bar>")
 })
 
 test_that("S7_methods(generic) returns empty df when no methods", {
@@ -49,7 +70,7 @@ test_that("S7_methods(generic) returns empty df when no methods", {
   res <- S7_methods(generic = gen)
   expect_s3_class(res, "data.frame")
   expect_equal(nrow(res), 0)
-  expect_named(res, c("generic", "package", "signature", "method"))
+  expect_named(res, c("generic", "package", "signature"))
 })
 
 test_that("S7_methods(class) scans attached generics", {
@@ -91,17 +112,6 @@ test_that("S7_methods() validates inputs", {
   })
 })
 
-test_that("the `method` column round-trips via eval(parse(...))", {
-  Foo <- new_class("Foo", package = NULL)
-  gen <- new_generic("gen", "x")
-  method(gen, Foo) <- function(x) "foo result"
-
-  res <- S7_methods(generic = gen)
-  m <- eval(parse(text = res$method[1]))
-  expect_s3_class(m, "S7_method")
-  expect_equal(m(Foo()), "foo result")
-})
-
 test_that("find_objects() returns matching names", {
   env <- new.env(parent = emptyenv())
   env$Foo <- new_class("Foo", package = NULL)
diff --git a/tests/testthat/test-method-register.R b/tests/testthat/test-method-register.R
index bd3fcc37..0500774a 100644
--- a/tests/testthat/test-method-register.R
+++ b/tests/testthat/test-method-register.R
@@ -296,6 +296,14 @@ describe("as_signature()", {
   })
 })
 
+test_that("S7_signature has format and print methods", {
+  foo <- new_generic("foo", c("x", "y"))
+  sig <- as_signature(list(class_integer, class_character), foo)
+
+  expect_equal(format(sig), "<integer>, <character>")
+  expect_snapshot(print(sig))
+})
+
 test_that("check_method returns TRUE if the functions are compatible", {
   foo <- new_generic("foo", "x", function(x, ...) S7_dispatch())
   expect_true(check_method(function(x, ...) x, foo))

From 3c990ba1d221e00f354763b0bb5f37d8dc988798 Mon Sep 17 00:00:00 2001
From: Hadley Wickham <h.wickham@gmail.com>
Date: Mon, 15 Jun 2026 07:59:19 -0500
Subject: [PATCH 9/9] Polish news

---
 NEWS.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/NEWS.md b/NEWS.md
index 0e9d64f5..3eff5e79 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -29,7 +29,7 @@
 * `prop()` no longer leaves an object in a broken state when a custom getter signals an error (#520, #640, #638).
 * `prop<-()` no longer fails when assigning a call or symbol to a property (#511, #633, #638).
 * New `prop_info()` returns a data frame summarising the properties of an S7 object or class, with one row per property and columns for name, default, class, getter, setter, and validator (#551).
-* New `S7_classes()`, `S7_generics()`, and `S7_methods()` are new introspection helpers. `S7_classes()` and `S7_generics()` list the S7 classes / generics defined in a given environment; pass `asNamespace("pkg")` to inspect a specific package (#335). `S7_methods()` returns a data frame of methods registered on a generic, or — analogously to `utils::methods(class = )` — registered for a class across all attached packages (#435).
+* New `S7_classes()`, `S7_generics()`, and `S7_methods()` introspection helpers. `S7_classes()` and `S7_generics()` list the S7 classes / generics defined in a given environment/package (#335). `S7_methods()` list methods methods registered on a generic or all methods associated with a class (across generics in attached packages) (#435).
 * `S7_dispatch()` now gives a clear error when called from a function that is not an S7 generic, e.g. `unclass(generic)()`, instead of failing with a confusing message (#684).
 * `S7_class()` now returns a class specification for any R object, not just S7 objects. It returns the matching `class_*` for base types, a `new_S3_class()` wrapper for S3 objects, and the S4 class for S4 objects, so the result can be passed directly to `method()` or other S7 dispatch helpers (#559).
 * `S7_class_desc()` is a new exported helper that formats a class specification as a short human-readable string (#594).