tests/testthat/_snaps/class.md

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

S7 classes: print nicely

Code
  foo2
Output
  <foo2> class
  @ parent     : <foo1>
  @ constructor: function(x, y) {...}
  @ validator  : <NULL>
  @ properties :
   $ x: <integer>
   $ y: <integer>
Code
  str(foo2)
Output
  <foo2/foo1/S7_object> constructor
   @ name       : chr "foo2"
   @ parent     : <foo1/S7_object> constructor
   @ package    : NULL
   @ properties :List of 2
   .. $ x: <S7_property> 
   ..  ..$ name     : chr "x"
   ..  ..$ class    : <S7_base_class>: <integer>
   ..  ..$ getter   : NULL
   ..  ..$ setter   : NULL
   ..  ..$ validator: NULL
   ..  ..$ default  : NULL
   .. $ y: <S7_property> 
   ..  ..$ name     : chr "y"
   ..  ..$ class    : <S7_base_class>: <integer>
   ..  ..$ getter   : NULL
   ..  ..$ setter   : NULL
   ..  ..$ validator: NULL
   ..  ..$ default  : NULL
   @ abstract   : logi FALSE
   @ constructor: function (x = integer(0), y = integer(0))  
   @ validator  : NULL
Code
  str(list(foo2))
Output
  List of 1
   $ : <foo2/foo1/S7_object> constructor

S7 classes: prints @package and @abstract details

Code
  foo
Output
  <S7::foo> abstract class
  @ parent     : <S7_object>
  @ constructor: function() {...}
  @ validator  : <NULL>
  @ properties :

S7 classes: checks inputs

Code
  new_class(1)
Condition
  Error:
  ! `name` must be a single string
Code
  new_class("foo", 1)
Condition
  Error:
  ! Can't convert `parent` to a valid class. Class specification must be an S7 class object, the result of `new_S3_class()`, an S4 class object, or a base class, not a <double>.
Code
  new_class("foo", package = 1)
Condition
  Error:
  ! `package` must be a single string
Code
  new_class("foo", constructor = 1)
Condition
  Error:
  ! `constructor` must be a function
Code
  new_class("foo", constructor = function() { })
Condition
  Error:
  ! `constructor` must contain a call to `new_object()`
Code
  new_class("foo", validator = function() { })
Condition
  Error:
  ! `validator` must be function(self), not function()

S7 classes: can't inherit from S4 or class unions

Code
  new_class("test", parent = parentS4)
Condition
  Error:
  ! `parent` must be an S7 class, S3 class, or base type, not an S4 class.
Code
  new_class("test", parent = new_union("character"))
Condition
  Error:
  ! Can't convert `X[[i]]` to a valid class. Class specification must be an S7 class object, the result of `new_S3_class()`, an S4 class object, or a base class, not a <character>.

S7 classes: can't inherit from an environment

Code
  new_class("test", parent = class_environment)
Condition
  Error:
  ! Can't inherit from an environment.

abstract classes: can't be instantiated

Code
  foo <- new_class("foo", abstract = TRUE)
  foo()
Condition
  Error in `S7::new_object()`:
  ! Can't construct an object from abstract class <foo>

abstract classes: can't inherit from concrete class

Code
  foo1 <- new_class("foo1")
  new_class("foo2", parent = foo1, abstract = TRUE)
Condition
  Error in `new_class()`:
  ! Abstract classes must have abstract parents

abstract classes: can use inherited validator from abstract class

Code
  foo2(x = 2)
Condition
  Error:
  ! <foo2> object is invalid:
  - @x has bad value

new_object(): gives useful error if called directly

Code
  new_object()
Condition
  Error in `new_object()`:
  ! `new_object()` must be called from within a constructor

new_object(): validates object

Code
  foo("x")
Condition
  Error:
  ! <foo> object properties are invalid:
  - @x must be <double>, not <character>
Code
  foo(-1)
Condition
  Error:
  ! <foo> object is invalid:
  - x must be positive

new_object(): runs each parent validator exactly once

Code
  . <- A()
Output
  A 
Code
  . <- B()
Output
  A B 
Code
  . <- C()
Output
  A B C

S7 object: displays nicely

Code
  foo <- new_class("foo", properties = list(x = class_double, y = class_double),
  package = NULL)
  foo()
Output
  <foo>
   @ x: num(0) 
   @ y: num(0) 
Code
  str(list(foo()))
Output
  List of 1
   $ : <foo>
    ..@ x: num(0) 
    ..@ y: num(0)

S7 object: displays objects with data nicely

Code
  text <- new_class("text", class_character, package = NULL)
  text("x")
Output
  <text> chr "x"
Code
  str(list(text("x")))
Output
  List of 1
   $ : <text> chr "x"

S7 object: displays list objects nicely

Code
  foo1(list(x = 1, y = list(a = 21, b = 22)), x = 3, y = list(a = 41, b = 42))
Output
  <foo1> List of 2
   $ x: num 1
   $ y:List of 2
    ..$ a: num 21
    ..$ b: num 22
   @ x: num 3
   @ y:List of 2
   .. $ a: num 41
   .. $ b: num 42

c(, ...) gives error

Code
  c(foo1, foo1)
Condition
  Error:
  ! Can not combine S7 class objects

can't create class with reserved property names

Code
  new_class("foo", properties = list(names = class_character))
Condition
  Error in `new_class()`:
  ! property can't be named: names
Code
  new_class("foo", properties = list(dim = NULL | class_integer))
Condition
  Error in `new_class()`:
  ! property can't be named: dim
Code
  new_class("foo", properties = list(dim = NULL | class_integer, dimnames = class_list))
Condition
  Error in `new_class()`:
  ! property can't be named: dim, dimnames

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