5.9 Object, Class, and Interface Utilities

(object? v) → boolean?

v : any/c

Returns #t if v is an object, #f otherwise.

(class? v) → boolean?

v : any/c

Returns #t if v is a class, #f otherwise.

(interface? v) → boolean?

v : any/c

Returns #t if v is an interface, #f otherwise.

(generic? v) → boolean?

v : any/c

Returns #t if v is a generic, #f otherwise.

(object=? a b) → eq?

a : object?

b : object?

Determines if two objects are the same object, or not; this procedure uses "eq?", but also works properly with contracts.

(object->vector object [opaque-v]) → vector?

object : object?

opaque-v : any/c = #f

Returns a vector representing object that shows its inspectable fields, analogous to struct->vector.

(class->interface class) → interface?

class : class?

Returns the interface implicitly defined by class.

(object-interface object) → interface?

object : object?

Returns the interface implicitly defined by the class of object.

(is-a? v type) → boolean?

v : any/c

type : (or/c interface? class?)

Returns #t if v is an instance of a class type or a class that implements an interface type, #f otherwise.

(subclass? v class) → boolean?

v : any/c

class : class?

Returns #t if v is a class derived from (or equal to) class, #f otherwise.

(implementation? v interface) → boolean?

v : any/c

interface : interface?

Returns #t if v is a class that implements interface, #f otherwise.

(interface-extension? v interface) → boolean?

v : any/c

interface : interface?

Returns #t if v is an interface that extends interface, #f otherwise.

(method-in-interface? sym interface) → boolean?

sym : symbol?

interface : interface?

Returns #t if interface (or any of its ancestor interfaces) includes a member with the name sym, #f otherwise.

(interface->method-names interface) → (listof symbol?)

interface : interface?

Returns a list of symbols for the method names in interface, including methods inherited from superinterfaces, but not including methods whose names are local (i.e., declared with define-local-member-names).

(object-method-arity-includes?   object             sym             cnt)   →   boolean?

object : object?

sym : symbol?

cnt : exact-nonnegative-integer?

Returns #t if object has a method named sym that accepts cnt arguments, #f otherwise.

(field-names object) → (listof symbol?)

object : object?

Returns a list of all of the names of the fields bound in object, including fields inherited from superinterfaces, but not including fields whose names are local (i.e., declared with define-local-member-names).

(object-info object)   →   (or/c class? false/c)   boolean?

object : any/c

Returns two values, analogous to the return values of struct-info: K%

• class: a class or #f; the result is #f if the current inspector does not control any class for which the object is an instance.

• skipped?: #f if the first result corresponds to the most specific class of object, #t otherwise.

(class-info class)

→   symbol? exact-nonnegative-integer? (listof symbol?) (any/c exact-nonnegative-integer? . -> . any/c) (any/c exact-nonnegative-integer? any/c . -> . any/c) (or/c class? false/c) boolean?

class : class?

Returns seven values, analogous to the return values of struct-type-info:

• name: the class’s name as a symbol;

• field-cnt: the number of fields (public and private) defined by the class;

• field-name-list: a list of symbols corresponding to the class’s public fields; this list can be larger than field-k because it includes inherited fields;

• field-accessor: an accessor procedure for obtaining field values in instances of the class; the accessor takes an instance and a field index between 0 (inclusive) and field-cnt (exclusive);

• field-mutator: a mutator procedure for modifying field values in instances of the class; the mutator takes an instance, a field index between 0 (inclusive) and field-cnt (exclusive), and a new field value;

• super-class: a class for the most specific ancestor of the given class that is controlled by the current inspector, or #f if no ancestor is controlled by the current inspector;

• skipped?: #f if the sixth result is the most specific ancestor class, #t otherwise.

(struct   (exn:fail:object exn:fail)   ())

Raised for class-related failures, such as attempting to call a method that is not supplied by an object.